Surgical resection of primary colon cancer

INTRODUCTION — The majority of primary cancers arising in the colon are adenocarcinomas. A surgical resection is the only curative treatment modality for localized colon cancer. The goal of surgical resection of primary colon cancer is complete removal of the tumor, the major vascular pedicles, and the lymphatic drainage basin of the affected colonic segment [1]. En bloc resection of contiguous structures is indicated if there is attachment or infiltration of the tumor into a potentially resectable organ or structure. Patients with symptoms of complicated disease (eg, obstruction, perforation) may require a staged approach to resection.

Surgical resection may also be indicated in selected patients with limited, potentially resectable metastatic disease (eg, in the liver or lung). (See "Potentially resectable colorectal cancer liver metastases: Integration of surgery and chemotherapy" and "Surgical resection of pulmonary metastases: Benefits, indications, preoperative evaluation, and techniques".)

The surgical management of the primary disease in patients with colon cancer is reviewed here. The epidemiology, clinical presentation, staging, and medical therapies used to treat colon cancer (eg, chemotherapy, radiation therapy), surgical treatment of metastatic disease, issues surrounding resection of the primary site in patients who present with metastatic disease, and prognosis following treatment of localized colon cancer are reviewed separately:

●(See "Epidemiology and risk factors for colorectal cancer".)

●(See "Clinical presentation, diagnosis, and staging of colorectal cancer".)

●(See "Overview of the management of primary colon cancer".)

●(See "Locoregional methods for management and palliation in patients who present with stage IV colorectal cancer", section on 'Management of the primary cancer'.)

Colon resection techniques are discussed elsewhere.

●(See "Overview of colon resection".)

●(See "Right and extended right colectomy: Open technique".)

●(See "Left colectomy: Open technique".)

●(See "Minimally invasive techniques: Left/sigmoid colectomy and proctectomy".)

PREOPERATIVE EVALUATION — For many patients, the diagnosis of colon cancer is made based upon biopsy of a polyp or polyps at the time of a screening colonoscopy. For others, the diagnosis is made because of symptoms such as occult gastrointestinal bleeding or abdominal pain. Regardless, the evaluation typically consists of the following components (see "Clinical presentation, diagnosis, and staging of colorectal cancer", section on 'Staging'):

●A detailed history and physical examination – Patients suspected of having a hereditary cancer syndrome based on family history should be referred to a genetics counselor for possible genetic testing, the result of which may impact surgical planning. (See "Lynch syndrome (hereditary nonpolyposis colorectal cancer): Clinical manifestations and diagnosis" and "MUTYH-associated polyposis", section on 'Clinical manifestations'.)

●Serum carcinoembryonic antigen (CEA) level – A baseline serum CEA level should be obtained preoperatively in all patients with colon cancer. Preoperative CEA level is an independent predictor of overall survival in stage I to III colon cancer [2]. (See "Clinical presentation, diagnosis, and staging of colorectal cancer", section on 'Tumor markers'.)

●Colonoscopy – Patients should undergo a full colonoscopy before surgery for colon cancer. Synchronous colon cancer has been reported to be present in 4 percent of patients with sporadic colon cancer [3] and synchronous adenomatous polyps in 30 to 50 percent [4,5]. If preoperative colonoscopy is not possible due to complicated disease, a full colonoscopy should be performed postoperatively. (See "Clinical presentation, diagnosis, and staging of colorectal cancer", section on 'Colonoscopy'.)

●Chest/abdomen/pelvis computed tomography (CT) scan – In the United States, the standard practice at most institutions is that all patients with stage II, III, or IV colon cancer undergo staging CT scans of the chest, abdomen, and pelvis prior to or following resection if not possible beforehand, such as in complicated disease. (See "Clinical presentation, diagnosis, and staging of colorectal cancer", section on 'Clinical presentation' and "Clinical presentation, diagnosis, and staging of colorectal cancer", section on 'Clinical staging evaluation'.)

In general, it is preferable to obtain radiographic staging studies preoperatively as the scan results will occasionally change surgical planning. Most patients with complicated colon cancer that requires emergency surgery (eg, perforation, obstruction) will have undergone CT of at least the abdomen and pelvis as part of their workup. Under these circumstances, there is no immediate need for other workup such as CT of the chest. Once the emergency situation has been resolved, the remainder of the workup can be completed. (See 'Complicated disease' below.)

CANDIDATES FOR RESECTION — Surgical resection is the only curative treatment modality for localized colon cancer, and it may also be indicated for selected patients with limited, potentially resectable metastatic disease (eg, in the liver or lung). (See "Potentially resectable colorectal cancer liver metastases: Integration of surgery and chemotherapy" and "Surgical resection of pulmonary metastases: Benefits, indications, preoperative evaluation, and techniques".)

Contraindications — Patients with unresectable metastatic disease are generally not candidates for resection of the primary colon tumor in the absence of symptoms or complications (eg, perforation, obstruction) attributable to the primary tumor. (See 'Synchronous metastatic disease' below and 'Complicated disease' below and 'Palliative surgery' below and 'With asymptomatic primary colon cancer' below.)

Increasing age may be accompanied by higher rates of medical comorbidity. Some patients may not be appropriate candidates for resection due to medical comorbidities. (See "Overview of colon resection", section on 'Medical risk assessment'.)

GENERAL PRINCIPLES — The goals of surgical resection of primary colon cancer are complete removal of the tumor, the major vascular pedicles, and the lymphatic drainage basin of the affected colonic segment. These goals can be achieved using an open or laparoscopic approach, but the specific clinical situation (eg, elective versus emergency colectomy) often dictates the approach. However, the same principles of resection that apply to open surgery for resecting colon cancer must also apply to the laparoscopic approach. (See 'Resection margins' below and 'Regional lymphadenectomy' below.)

Open versus laparoscopic colectomy — Meta-analyses of randomized trials (the largest trial and two of the meta-analyses are described below) demonstrate faster recovery with no detrimental impact on recurrence or survival for laparoscopic compared with open colectomy for the treatment of colon cancer [6-15]. Thus, when a surgeon experienced with advanced laparoscopic colectomy techniques is available, we recommend laparoscopic-assisted colectomy rather than open colectomy for patients with uncomplicated localized colon cancers who have not had prior extensive abdominal surgery. For complicated colon cancers, an open approach is frequently necessary.

●In the largest trial, the United States Intergroup Clinical Outcomes of Surgical Therapy (COST) trial, 872 patients with colonic adenocarcinoma were randomly assigned to open or laparoscopic colectomy by credentialed surgeons who each performed at least 20 laparoscopic resections and underwent videotape analysis of their technique before enrolling patients in the study [10,11]. Operative time was significantly longer in the laparoscopic group (150 versus 95 minutes), and 21 percent of laparoscopic cases required conversion to an open procedure [10]. On the other hand, the laparoscopic group had modestly but significantly shorter durations of hospital stay (five versus six days) and parenteral analgesic use (three versus four days). There were no significant differences in intraoperative or postoperative complications, perioperative mortality rates, readmission or reoperation rates [10], or rates of surgical wound recurrence [11]. At a median follow-up of seven years, there were no significant differences in the five-year disease-free survival (69 versus 68 percent in the laparoscopic and open colectomy groups, respectively) or overall survival (76 versus 75 percent).

●In another trial (ALCCaS) involving 425 patients with colon cancer, those who underwent laparoscopic resection reported better quality-of-life scores in appetite, insomnia, pain, fatigue, daily living, and health, compared with patients who underwent open surgery at two days, two weeks, and two months postoperatively [16].

●Long-term outcomes from laparoscopic versus open colon resection have been addressed in two meta-analyses of randomized trials, most of which enrolled exclusively or predominantly patients with colon cancer [6,7]. One analyzed results from seven published randomized trials, while the other focused upon four trials with the endpoint of survival that enrolled more than 150 patients [9-12,17]. Both concluded that laparoscopic colectomy provides oncologic outcomes, including number of lymph nodes harvested, disease recurrence, and overall survival, that are comparable to those achieved with an open approach. In the larger of the two meta-analyses (n = 1536), three-year disease-free survival rates for laparoscopic versus open colectomy were 75.8 and 75.3 percent, respectively (95% CI of the difference, -5 to 4 percent); three-year overall survival rates were also similar (82.2 versus 83.5 percent; 95% CI -3 to 5 percent) [6]. Of the seven trials reporting this outcome, only 3 of 826 patients randomized to laparoscopic surgery developed an incisional recurrence, compared with 1 of 801 patients undergoing open surgery [7].

●In addition, patients who undergo laparoscopic colectomy for node-positive cancer may be more likely to initiate adjuvant chemotherapy. In a study of 12,849 patients who underwent colectomy for stage III colon cancer, adjuvant chemotherapy was given more frequently to patients receiving the laparoscopic approach as compared with open colectomy (72 percent versus 67 percent) [18]. Adjuvant chemotherapy is typically initiated only after recovery from surgery; laparoscopy may be associated with a decrease in complications and therefore a faster postoperative recovery. (See "Adjuvant therapy for resected stage III (node-positive) colon cancer".)

Techniques for open and laparoscopic colon resection are reviewed separately. (See "Overview of colon resection" and "Right and extended right colectomy: Open technique" and "Left colectomy: Open technique" and "Minimally invasive techniques: Left/sigmoid colectomy and proctectomy".)

Resection margins — Proximal and distal resection margins should be at least 5 to 7 cm from the tumor [19-21]. These margins should allow for an adequate resection of the appropriate segment of the bowel with its vascular supply and associated lymphatics. For patients undergoing right hemicolectomy, the length of ileum resected does not influence local recurrence rates [19]. (See 'Cecum or right colon' below.)

Radial margin positivity is rare with colon cancer resections. A retrospective study of 984 patients who underwent colon cancer resections identified 52 patients (5.3 percent) with an involved radial margin [22]. A positive radial margin conferred both a worse overall survival (hazard ratio [HR] 3.39, 95% CI 2.41-4.77) and a worse disease-specific survival (HR 2.03, 95% CI 1.43-2.89). In addition, in a subgroup analysis of the 16 patients who had no baseline metastasis at presentation, a positive radial margin was associated with a significantly increased risk of distant disease recurrence (38 versus 13 percent) as well as a nonstatistically significant increase in local recurrences (6.3 versus 1.3 percent). The subgroup analysis needs to be interpreted with caution due to the small number of patients and events.

Thus, patients who are suspected of having a positive radial margin either preoperatively or intraoperatively should undergo extended surgery including en bloc resection of adjacent organs to achieve a negative margin. (See 'Locally advanced cancer' below.)

Regional lymphadenectomy — Regional lymphadenectomy provides prognostic information and guides postoperative management, such as chemotherapy administration.

The tumor-bearing colon should be removed en bloc with the associated mesentery to the origin of the named primary feeding vessel without any defect in the mesentery. Such a resection will include the regional mesenteric lymph nodes along the course of major mesenteric vessels and along the vascular arcades (intermediate and central nodes) (figure 1), as well as those adjacent to the colon along its mesocolic border (pericolonic nodes) [23]. The extent of such a regional lymphadenectomy is sometimes referred to as a D2 excision, particularly in the Japanese literature. An example of this type of resection is given in the figure (figure 2A-B) and contrasted with the resection used for benign disease. (See "Overview of colon resection", section on 'Benign versus malignant disease'.)

Some surgeons perform an extended lymphadenectomy beyond the primary feeding vessel and associated central lymph node basin; such practice is variably referred to in the literature as "high ligation," "central vascular ligation," "complete mesocolic excision (CME)," or "D3 excision." (See "Right and extended right colectomy: Minimally invasive techniques", section on 'Lymphadenectomy'.)

As an example, in two retrospective studies by the same group from a national database of patients with stage I to III colon cancer, those who underwent complete mesocolic excision in one hospital had better four-year disease-free survival (86 versus 73 percent after propensity score matching) [24] and five-year recurrence rate (9.7 versus 17.9 percent) [25] compared with those who underwent colon resection with conventional lymphadenectomy at three other hospitals. However, the five-year overall survival was not different between the groups [24].

However, routine performance of extended lymphadenectomy beyond the primary feeding vessel and associated central lymph node basin without any clinical justification (eg, clinically positive nodes) is not the standard of care. Metastasis to central lymph nodes occurs in 1 to 8 percent of patients with colon cancer and is most commonly seen with T3 or T4 tumors [26]. Metastasis to central lymph nodes but not more peripheral nodes (ie, "skip metastasis") occurs in fewer than 2 percent of cases [27].

A large multicenter Chinese trial (RELARC) of 995 patients with right colon cancers reported that laparoscopic right colectomy with CME resulted in a similar overall complication rate to that of a D2 dissection (20 versus 22 percent) but a greater number of vascular injuries (3 versus 1 percent) [28]. Central lymph node metastasis was detected in 3 percent of those who underwent CME, but there was no skip metastasis.

A preliminary analysis of an ongoing trial (COLD) that compared D2 with D3 lymphadenectomy found similar morbidity rates (47 versus 48 percent). The lymph node yield was also similar (26.6 versus 27.8), but a higher percentage of lymph nodes obtained with D3 dissection were positive than with D2 dissection (46 versus 26 percent). Good-quality complete mesocolic excisions were more frequently seen with D3 dissection. The trial has only enrolled 100 patients so far, and the oncologic outcomes have not been published [29].

There is a direct correlation between the number of lymph nodes evaluated per patient after surgical resection and survival [30]. Examination of fewer than 12 lymph nodes is a high-risk feature for stage II colon cancer, which increases the risk of recurrence to that of stage IIIA disease [31,32]. As such, consensus guidelines recommend that at least 12 lymph nodes be assessed for adequate staging [19,33-35]. Adjuvant chemotherapy may be offered to those who have fewer than 12 lymph nodes examined, even if they have no demonstrable metastatic disease in the examined nodes [36,37]. (See "Adjuvant therapy for resected stage II colon cancer".)

Role of sentinel node mapping — The sentinel lymph node (SLN) concept is based upon the observation that tumor cells migrating from a primary tumor metastasize to one or a few lymph nodes (LNs) before involving other LNs. Injection of vital blue dye and/or radiolabeled colloid around the area of the tumor permits identification of an SLN in the majority of patients, and its status accurately predicts the status of the remaining regional LNs. The concept of SLN biopsy as a less morbid alternative to complete regional lymph node dissection has gained traction in patients with breast cancer and melanoma, but its utility for other tumor types has yet to be demonstrated. (See "Overview of sentinel lymph node biopsy in breast cancer" and "Evaluation and management of regional nodes in primary cutaneous melanoma" and "Evaluation and management of regional nodes in primary cutaneous melanoma", section on 'SLNB timing and technique'.)

SLN mapping is not considered a standard approach to nodal staging in colon cancer and does not replace standard lymphadenectomy. A meta-analysis and a systematic review reported that SLN mapping for colon cancer had a sensitivity of 78 to 93 percent and a false negative rate of 4 percent (range 0 to 15 percent) [38,39]. Another meta-analysis of 11 studies using a newer tracer (indocyanine green) reported a pooled sensitivity and specificity of 64 and 65 percent [40].

When LNs retrieved by SLN mapping are studied by immunohistochemistry and/or molecular techniques ("ultra-staging"), upstaging was reported in 11 to 29 percent of patients with otherwise node-negative colon cancer (by standard hematoxylin and eosin [H&E] staining) [41-43]. However, there is uncertainty surrounding the prognostic significance of these micrometastases [23]. The newest 2017 (eighth edition) revision of the Tumor, Node, Metastasis (TNM) staging classification defines micrometastases of 0.2 to 2 mm as N1 disease and those <0.2 mm (including isolated tumor cells) as N0(i+) disease. (See "Pathology and prognostic determinants of colorectal cancer", section on 'Nodal micrometastases'.)

The Cancer and Leukemia Group B 80001 trial examined both sentinel and nonsentinel lymph nodes of colon cancer by standard histopathology and immunohistochemistry. By either criterion, examination of the sentinel nodes alone failed to accurately predict the presence of either conventionally defined nodal metastases or micrometastases in the nodal basin [44].

COLON RESECTION

Malignant polyp — The majority of colorectal cancers arise from polyps (adenomas). The malignant potential of an adenoma depends on its size, histology, and degree of dysplasia. It is believed that the transformation from normal mucosa to adenoma, dysplasia, and then to invasive cancer takes many years. An invasive cancer, which is defined by penetration of the muscularis mucosa by malignant cells into the submucosa (T1), has the potential to metastasize to lymph nodes and distant sites. It is estimated that 5 percent of endoscopically resected and 20 percent of endoscopically unresectable colorectal adenomas contain invasive cancer [45,46].

The management of a malignant polyp containing invasive carcinoma must be individualized. Endoscopic management is sufficient for pedunculated or sessile malignant polyps that can be removed in one piece and have none of the following high-risk features [1,47-49]:

●Poorly differentiated histology.

●Lymphovascular invasion (LVI) or perineural invasion (PNI).

●Tumor budding (foci of isolated cancer cells or a cluster of five or fewer cancer cells at the invasive margin of the polyp).

●Cancer at the resection margin.

●Submucosal invasion depth ≥1 mm.

Practically, LVI and poorly differentiated histology are the most commonly diagnosed high-risk features in a malignant polyp; deep submucosal invasion usually requires endoscopic submucosal resection rather than simple polypectomy, while PNI and tumor budding are usually seen in colectomy specimens.

Polyps with one or more of these high-risk features are associated with an increased incidence of residual cancer and/or lymph node metastases [50,51]. As such, their presence indicates the need for radical resection. In addition, any cancer in a nonpedunculated or pedunculated lesion resected piecemeal or a pedunculated polyp that could not be properly oriented in the pathology department to provide optimal pathologic assessment is an indication for surgery [49].

If invasive cancer is suspected at the time of polypectomy, the endoscopist usually tattoos the area by injecting a permanent marker at the site of the polypectomy. In this manner, the site can be localized during surgical exploration. If the area was not tattooed at the time of polypectomy, an attempt at finding the polypectomy site and tattooing should be performed endoscopically prior to surgery. If this is not possible, intraoperative colonoscopy should be performed to identify the polypectomy scar. (See "Tattooing and other methods for localizing gastrointestinal lesions".)

Tumors invading into or through the muscularis propria (T2 or above lesion) are no longer considered malignant polyps but bona fide colon cancers and staged and treated accordingly. (See 'Localized cancer' below.)

The management of malignant colorectal polyps is also discussed elsewhere. (See "Overview of the management of primary colon cancer", section on 'Management of carcinoma in a polyp' and "Overview of colon polyps", section on 'High-grade dysplasia or cancer'.)

Localized cancer — Segmental resection alone may be sufficient for primary tumor removal; however, a wider resection may be required to perform a regional lymphadenectomy, which requires division of the major blood vessels at their origin to enable removal of draining intermediate and central lymph nodes. The extent of the resection depends upon the location of the tumor:

Cecum or right colon — A right hemicolectomy is usually performed for cancer of the cecum and ascending colon and for some hepatic flexure cancers (figure 3). The general principles for performing the operative procedure are described elsewhere. (See "Overview of colon resection" and "Right and extended right colectomy: Open technique".)

Transverse colon — Transverse colectomy is a procedure that is uncommonly performed, as cancers are generally either to the right or left of the midline, and therefore, hemicolectomy (extended right or left) should be performed to achieve an adequate lymphadenectomy. An extended right colectomy is typically performed for cancer of the hepatic flexure and proximal transverse colon (figure 4) [52]. The general principles for performing the operative procedure are described elsewhere. (See "Overview of colon resection" and "Right and extended right colectomy: Open technique".)

In the case of "true" midtransverse cancers, a transverse colectomy can be performed. A transverse colectomy may be undertaken for midtransverse colon cancers as long as satisfactory resection margins and an adequate lymphadenectomy can be obtained (figure 5). The transverse colon is resected along with the middle colic vessels and its mesentery. However, the surgeon must ensure that an adequate lymphadenectomy is performed and that there is no tension at the anastomosis. If any of these factors are not met, the patient is best served by an extended right or left hemicolectomy.

In a Korean retrospective study of 1066 patients with transverse colon cancer, 70.4, 11.9, and 17.7 percent underwent extended right, transverse, and extended left colectomy, respectively, at the surgeon's discretion [53]. A propensity-matched analysis revealed no significant differences in overall or disease-free survival after transverse versus extended colectomy. In multivariate analysis, only node-positive disease (hazard ratio [HR] 2.035, 95% CI 1.188-3.484), tumors with ulcerative morphology (HR 3.643, 95% CI 1.132-11.725), and the presence of vascular invasion (HR 2.569, 95% CI 1.455-4.538) predicted poor survival.

Splenic flexure — Colon cancers at the splenic flexure primarily metastasize to lymph nodes along the left colic pedicle [54] but occasionally also along the superior mesenteric artery (SMA) and its tributaries [55,56]. Thus, the optimal extent of surgical resection is controversial. Splenic flexure colon cancers can be managed by a left hemicolectomy, an extended left colectomy, or an extended right hemicolectomy.

●A left hemicolectomy involves division of the left branch of the middle colic artery (at its takeoff from the middle colic artery) and the left colic artery (at its takeoff from the inferior mesenteric artery [IMA]; with the IMA remaining intact). The distal transverse colon, splenic flexure colon, and descending colon are resected [54,55,57-59].

●An extended left colectomy ligates the left branch of the middle colic and the origin of the IMA with resection of the distal transverse colon, splenic flexure colon, descending colon, and sigmoid colon.

●An extended right colectomy, also referred to as a subtotal colectomy by some, resects the terminal ileum, cecum, ascending colon, transverse colon, and proximal descending colon. The ileocolic, right colic, middle colic, and left colic arteries are ligated. A small bowel to descending or sigmoid colon, or rectal, anastomosis is performed [54,55,57-59].

The decision about which procedure to perform will depend on several factors, including preoperative imaging (paying special attention to the distribution of lymphadenopathy), adequacy of blood supply with attention to calcifications at the origin of the blood vessels, whether the tumor is obstructing or not, the potential for an inherited syndrome (Lynch syndrome), surgeon preference, and functional status of the patient. Ultimately, the decision on which procedure to perform will be influenced by the ability to perform an adequate lymphadenectomy and a well-vascularized, tension-free anastomosis. There is no significant difference in oncologic outcomes (eg, lymph node yield, R0 rate, and survival) [57-61].

Most of the time the surgical procedure for a splenic flexure cancer should be a left hemicolectomy with a colo-colonic anastomosis at the distal descending or sigmoid colon. In a systematic review of 12 retrospective studies (569 patients), 23 percent underwent extended right colectomy and 77 percent underwent left hemicolectomy [59]. A subsequent retrospective study of 313 patients with propensity score matching reported no significant difference between the three techniques in terms of survival and complications. Patients who underwent extended right hemicolectomy required a longer hospital stay [62].

The left colic vessels, inferior mesenteric vein, and left branch of the middle colic should be divided. If there is no lymphadenopathy at the origin of the inferior mesenteric artery, this vessel can be preserved, but the left colic vessels (ascending branch) should be ligated. The choice between a left hemicolectomy and an extended left colectomy is primarily based on the location of the lesion and the distribution of lymphadenopathy.

If there is a colonic obstruction or the potential for Lynch syndrome, consideration for an extended right hemicolectomy performed with an ileo-distal descending, ileo-sigmoid [59], or even an ileorectal anastomosis may be appropriate. In a series of 80 patients who underwent emergency splenic flexure cancer resection, 75 for obstruction, 55 (61 percent) underwent extended right colectomy [61].

Some surgeons prefer an extended right hemicolectomy because there is less tension on the anastomosis and theoretically better vascular supply. However, the disadvantage of an extended right hemicolectomy is that the ileocecal valve is removed and patients will experience more frequent bowel movements. Although most of the time the bowel adapts and patients eventually do well, this is something to consider in the older adult population as these patients may have more issues with bowel function and at times may even need bulking agents or medication to decrease the number of bowel movements.

Left colon — A left hemicolectomy is appropriate for tumors in the distal transverse or descending colon and for selected patients with proximal sigmoid colon cancer (figure 6 and figure 2A). In select patients, a segmental colectomy may be performed as long as adequate resection margins and lymphadenectomy are achieved. The general principles for performing the operative procedure are described elsewhere. (See "Left colectomy: Open technique" and "Minimally invasive techniques: Left/sigmoid colectomy and proctectomy".)

Sigmoid colon — For sigmoid colon cancers, sigmoid colectomy is appropriate (figure 7). The inferior mesenteric artery is divided at its origin, and dissection proceeds just under the superior rectal vessels toward the pelvis until adequate margins are obtained.

Synchronous colon cancer — Synchronic cancers refer to a second primary colon cancer diagnosed at the same time or within one year from when the index cancer is diagnosed [63]. It occurs in 4 percent of sporadic colon cancer cases [3].

Synchronic colon cancers can be treated with two separate resections or one extended resection; a subtotal or a total abdominal colectomy may be performed if there are synchronous neoplasms on the right and left sides of the colon (figure 8).

The extent of resection is also influenced by any underlying colonic diseases. As examples, carcinoma in a patient with chronic ulcerative colitis is usually treated with a proctocolectomy with or without an ileal pouch anal anastomosis (IPAA) [64]. For patients with hereditary nonpolyposis colorectal cancer (HNPCC, Lynch syndrome) who present with a colon cancer, total abdominal colectomy with consideration for hysterectomy and bilateral salpingo-oophorectomy in females is the procedure of choice [65]. Total abdominal colectomy or proctocolectomy with IPAA are procedures that can be offered to patients with familial adenomatous polyposis (FAP) and MUTYH-associated polyposis. (See "Lynch syndrome (hereditary nonpolyposis colorectal cancer): Clinical manifestations and diagnosis" and "MUTYH-associated polyposis", section on 'Colorectal cancer surveillance'.)

Locally advanced cancer — Approximately 10 percent of patients with colon cancer have invasion of contiguous organs or inflammatory adhesions involving neighboring structures. En bloc resection of contiguous structures is indicated if there is attachment or infiltration of the tumor into any organ or structure. The plane of adherence between the colonic tumor and the adjacent organ(s) should not be disrupted, because 34 to 84 percent of these adhesions are malignant and transection of tumor could further impair prognosis [66-68].

Guidelines from the National Comprehensive Cancer Network (NCCN) [69], National Cancer Institute (NCI), and American Society of Colon and Rectal Surgeons, as well as quality performance indicators for colorectal cancer surgery developed by an independent group, emphasize that appropriate surgical management for colon cancers that grow through the bowel wall into adjacent structures or organs (eg, T4 disease) should include multivisceral resection with a negative margin of the adjacent structure (R0 resection) [19,34,35].

Multivisceral resection is associated with improved local control and overall survival [70-75]. As an example, of 121 patients who underwent multivisceral resection for locally advanced colon cancer between 2007 and 2014, 93 percent achieved an R0 resection. The estimated five-year overall survival was 70.8 percent; recurrent disease was diagnosed in 20 percent of patients after a median follow-up of 28 months [76]. In some series, long-term outcomes are comparable to those of patients undergoing standard resection who do not have adjacent organ adhesions [71,73], although perioperative morbidity rates may be higher [71].

If the surgeon anticipates the need for postoperative radiation therapy, consideration should be given to placing surgical clips at the resected tumor bed margins to better direct therapy. Occasionally, if omentum is available, an omental flap could be utilized to try to exclude small bowel from the radiation field. (See "Overview of the management of primary colon cancer", section on 'Benefit of postoperative radiation therapy'.)

Synchronous metastatic disease — The indications for and sequence of colon resection in patients who present with stage IV disease are discussed below. (See 'Metastatic disease' below.)

COMPLICATED DISEASE — For patients with complications related to the primary tumor (eg, bleeding, obstruction, perforation), the decision to proceed with surgery needs to be individualized depending on the presenting symptoms and signs as well as the medical condition of the patient. Patients with perforated tumor and generalized peritonitis need urgent surgery; however, depending upon the clinical scenario, hemodynamically stable patients with a localized abscess, bowel obstruction, or mild-to-moderate gastrointestinal bleeding benefit from staging evaluation to determine the choice and sequence of treatment.

●For patients without metastatic disease, curative resection is the goal, using either a one-stage or two-stage approach. (See 'Colonic perforation' below and 'Colonic obstruction' below.)

●For patients who have synchronous metastatic disease, systemic chemotherapy or resection of the metastatic lesions may be options. The goal of treatment is to manage the immediate complications, which may involve tumor resection but can include nonsurgical options (eg, stenting to relieve obstruction, angioembolization for bleeding). (See 'Synchronous colon cancer' above and 'Palliative surgery' below.)

●Patients with unresectable metastases are managed to palliate their symptoms. (See 'Metastatic disease' below.)

Colonic bleeding — Although colon cancer is commonly associated with chronic blood loss, acute massive colonic bleeding is a rare but potentially lethal complication. Patients who present with massive lower gastrointestinal bleeding should be resuscitated and the source of bleeding localized with computed tomographic (CT) angiography, conventional angiography, or colonoscopy. (See "Approach to acute lower gastrointestinal bleeding in adults".)

The initial attempt to stop bleeding should be made with nonsurgical methods such as colonoscopy or angioembolization [77,78]. Surgical intervention is required if nonsurgical methods fail to localize or control bleeding, in which case an oncologic resection should be performed.

Colonic perforation — Patients who have a perforated colon cancer have worse survival compared with those who have a colon cancer that is not perforated [79].

Treatment options in patients with tumor perforation depend upon the patient's overall condition and whether peritonitis is localized or generalized. If the patient is stable and peritonitis is not generalized, tumor resection with a primary anastomosis can be performed in appropriate surgical candidates. Primary anastomosis is not performed in the clinical setting of diffuse peritonitis or free perforation and/or if the patient is medically unstable. (See "Overview of gastrointestinal tract perforation".)

For patients with a localized fluid collection or abscess, percutaneous drainage can be performed. However, if transabdominal drainage is performed, there is a potential for seeding of the drain tract, and therefore, at the time of definitive resection, consideration should be given to resection of the drain tract and rim of the abdominal wall. Similarly, perforation may cause the tumor to adhere to other organs, and an en bloc resection may be necessary.

Colonic obstruction — Optimal management of an obstructing colon cancer depends upon the condition of the patient and the tumor location. Options include immediate surgery versus endoscopic stent decompression followed by interval surgery.

For surgical candidates, surgical options further include resection of the tumor with a primary anastomosis with or without a temporary proximal diversion, resection without an anastomosis and with an end colostomy, and proximal diversion with a mucous fistula or a loop colostomy to temporize the situation, followed by elective definitive resection at a second operation.

In general, the preferred surgical treatment is resection of the obstructing lesion and primary anastomosis with or without proximal diversion, but the choice of procedure(s) depends on the location of the tumor and other factors:

●For patients with obstructing right-sided cancers, right colectomy or extended right colectomy and primary ileocolonic anastomosis without proximal diversion can be safely performed since the right and transverse colon have low bacterial counts.

●Some studies suggest that obstructing left-sided lesions can also be safely managed with a one-stage procedure with acceptable morbidity [80,81]. As an example, in a retrospective study of 243 consecutive patients who underwent emergency surgery for obstructing colon cancer at Queen Mary's Hospital in Hong Kong, there were no statistically significant differences in hospital mortality or anastomotic leak rates among patients who underwent resection and primary anastomosis regardless of tumor location (right- versus left-sided) [80]. Nevertheless, many surgeons routinely perform a temporary proximal diverting colostomy following resection of an obstructing left-sided colon cancer.

For patients who are not good candidates for surgery, a temporizing approach for an obstructing cancer is endoscopic placement of an expandable metal stent. A meta-analysis of seven randomized trials found that 77 percent of patients had successful stent placement, and those treated with stenting had higher rates of primary anastomosis and lower rates of permanent ostomy but similar mortality compared with patients who underwent surgery. However, 7 percent of patients had colonic perforation at stent insertion; another 14 percent had "silent" (contained) perforation discovered in the colectomy specimen [82]. A concern for decreased survival in patients who suffer stent-related perforation led multiple endoscopic societies to recommend against stenting for obstructed but curable patients who are good surgical candidates. The same societies recommended for stenting in poor surgical candidates [83,84]. (See 'With symptomatic primary colon cancer' below.)

Enteral stenting in the setting of an obstruction from cancer is reviewed separately. (See "Enteral stents for the management of malignant colorectal obstruction".)

Timing of ostomy closure — Although restoration of bowel continuity by means of a tension-free primary anastomosis is ideal for patients undergoing colectomy, patients with complicated disease may require colostomy. (See 'Colonic perforation' above and 'Colonic obstruction' above.)

If an ostomy was performed at the time of primary colon surgery, the timing of stoma closure depends on various factors. Most importantly, resolution and recovery from the events that led to the decision to create the stoma (eg, perforation, generalized peritonitis, obstruction, and cardiovascular instability) must have taken place. If adjuvant chemotherapy is being administered, closure should be delayed to avoid unnecessary treatment delays.

If a primary anastomosis was performed, it should be studied for integrity and patency prior to closure of the stoma. If the entire colon was not evaluated prior to the stoma formation due to the urgent situation or due to an obstructing tumor, colonoscopy is indicated prior to ostomy closure. Ostomy closure is also discussed in another topic. (See "Overview of surgical ostomy for fecal diversion", section on 'Ostomy reversal'.)

METASTATIC DISEASE — Initial management of patients who present with stage IV disease is individualized. In general, the choice and sequence of treatment is guided by the presence or absence of symptoms or complications related to the primary tumor and whether or not the metastatic lesions are potentially resectable.

Resectable metastatic disease

Isolated liver or lung metastasis — For patients with potentially resectable metastases in the liver or lung, an aggressive surgical approach is warranted for both the primary and metastatic sites. Although the sequence of treatment may differ, medically fit patients with resectable hepatic and/or pulmonary metastases will generally benefit from curative resection of the metastases [85,86]. (See "Locoregional methods for management and palliation in patients who present with stage IV colorectal cancer", section on 'Management of the primary cancer' and "Potentially resectable colorectal cancer liver metastases: Integration of surgery and chemotherapy" and "Surgical resection of pulmonary metastases: Benefits, indications, preoperative evaluation, and techniques" and "Surgical resection of pulmonary metastases: Outcomes by histology", section on 'Colorectal cancer'.)

Isolated ovarian metastasis — Isolated ovarian metastases occur in approximately 3 to 8 percent of women with colon cancer, both at the time of colorectal cancer diagnosis and as a site of metachronous disease spread [87,88]. While it is generally acknowledged that ovarian metastases (particularly if synchronous and bilateral) represent a poor prognostic factor, complete resection of isolated ovarian metastases may improve survival. If one ovary is involved with disease, a bilateral oophorectomy should be performed because of the potential for microscopic disease in the other ovary as well as of the development of metachronous metastases [88]. Resection of clinically apparent ovarian metastases is discussed elsewhere. (See "Locoregional methods for management and palliation in patients who present with stage IV colorectal cancer", section on 'Ovarian metastases'.)

Prophylactic oophorectomy for normal-appearing ovaries during a primary colon cancer resection is not recommended, as there are no data that support a survival advantage for the procedure.

Isolated peritoneal carcinomatosis — In up to 35 percent of patients with peritoneal metastatic colon cancer, the metastasis is confined to the peritoneum alone [89,90]. In such patients, treatment decisions should be individualized and made with multidisciplinary input; options include systemic chemotherapy and cytoreductive surgery with or without intraperitoneal chemotherapy, the latter ideally in a clinical trial, both of which are further discussed in another topic. (See "Locoregional methods for management and palliation in patients who present with stage IV colorectal cancer".)

Unresectable metastatic disease — In the setting of unresectable metastatic disease, patients are managed according to the severity of the symptoms or complications relative to the primary site and the medical condition of the patient. (See 'Complicated disease' above and 'Palliative surgery' below.)

With asymptomatic primary colon cancer — Whether to resect the primary tumor in asymptomatic patients who have unresectable metastatic disease is controversial. Given the relatively low risk of bleeding (3 percent) or obstruction/perforation (7 to 14 percent) and the relatively high rates of perioperative morbidity, asymptomatic patients with stage IV disease can be initially managed conservatively [91-98]. We agree with guidelines from the National Comprehensive Cancer Network [69] that suggest not performing colon resection unless there is imminent risk of developing significant complications. (See "Locoregional methods for management and palliation in patients who present with stage IV colorectal cancer", section on 'Asymptomatic'.)

A Japanese randomized trial (JCOG 1007) reported that in asymptomatic patients with unresectable metastatic disease, primary tumor resection followed by chemotherapy had no survival advantage over chemotherapy alone [99]. This finding supports nonoperative management as the standard of care for asymptomatic patients with incurable metastatic colon cancer.

With symptomatic primary colon cancer — For symptomatic patients with advanced unresectable metastatic disease, limited surgery to manage complications is an option in good-risk surgical candidates. If the patient is not a surgical candidate because of comorbidities, high operative risk(s), decreased life expectancy, or refusal of surgery, nonsurgical options (eg, stenting) are preferred. (See "Locoregional methods for management and palliation in patients who present with stage IV colorectal cancer", section on 'Nonsurgical palliative options'.)

PALLIATIVE SURGERY — The methods for surgical palliation for patients with symptomatic colon or rectal cancer with incurable metastatic disease include:

●Resection of cancer and primary anastomosis

●Diverting end colostomy with mucous fistula

●Bypass procedure

For patients who can tolerate an intra-abdominal procedure, the optimal palliative procedure is a resection with a primary anastomosis. However, resection or primary anastomosis may not be possible in all clinical settings, because of extensive local disease involving adjacent structures or serious comorbid illnesses. In these situations, a diverting end colostomy with creation of a mucous fistula is the procedure of choice, especially in patients with distal colonic tumors. The mucous fistula decompresses the secretions from the distally obstructed segment of bowel. An end colostomy rather than a loop colostomy is preferred because it is easier to manage with fewer complications. (See "Overview of surgical ostomy for fecal diversion", section on 'Complications' and "Ileostomy or colostomy care and complications", section on 'Ostomy complications'.)

For patients with unresectable obstructing cancers, a bypass between the small bowel and the colon distal to the obstruction can be performed. However, if the patient has a competent ileocecal valve, there is potential for distention of the bypassed segment and eventual closed loop obstruction due to the accumulation of secretions in the bypassed colon. In patients with a competent ileocecal valve identified preoperatively on imaging, consideration should be given to an ostomy as opposed to bypass secondary to the potential risks. Alternatively, without clear evidence to determine ileocecal valve competence, the cecum can be tacked to the abdominal wall with seromuscular sutures, and surgical clips can be placed in the abdominal wall to mark the area where a potential percutaneous drain can be placed at a later time if necessary.

Regardless of the method of surgical palliation, the laparoscopic approach to colorectal resection is preferred to minimize the risk of postoperative complications [100]. While there are no data from randomized trials or prospective studies regarding the optimal approach (open versus laparoscopic) for surgical palliation, we believe the data from trials of colectomy for colon resection for colorectal cancer in the nonpalliative setting are directly applicable here. (See 'Open versus laparoscopic colectomy' above.)

LOCOREGIONAL RECURRENCE — Isolated local and regional recurrences occur in approximately 3 to 12 percent of patients who have undergone a primary colon cancer resection with curative intent [101-103]. Curative intent is defined as histologically negative margins of resection and no evidence of synchronous unresectable distant disease.

Locoregional recurrences are classified into four categories: anastomotic, mesenteric/nodal, retroperitoneal, and peritoneal [104]. Factors associated with recurrence include bowel perforation, fistulization, T3 and T4 size lesions (table 1), emergency surgery, poorly differentiated tumors, and cancers located in the hepatic flexure or sigmoid colon [101,102].

Although there are no prospective trials to guide therapy, the management of these patients is typically multidisciplinary and may include chemotherapy, chemoradiotherapy, or intraoperative radiation therapy, in addition to surgery. (See "Potentially resectable colorectal cancer liver metastases: Integration of surgery and chemotherapy", section on 'Systemic chemotherapy'.)

Patients suspected of having a locoregional recurrence should undergo comprehensive restaging, including a computed tomography (CT) scan of the chest, abdomen, and pelvis and a colonoscopy. Because of its greater sensitivity for distant metastatic disease, a positron emission tomography (PET) scan is indicated if staging CT scans are negative. (See "Clinical presentation, diagnosis, and staging of colorectal cancer", section on 'Positron emission tomography scans'.)

A major purpose of the restaging workup is to identify candidates for a salvage resection. Approximately 30 percent of patients with isolated recurrent locoregional colon cancer will qualify and derive long-term benefit from aggressive surgical resection of the recurrent disease. The most important prognostic factor is the ability to achieve an R0 resection (microscopic negative margins). In a systematic review, patients who underwent an R0 resection had a three-year overall survival of 58 percent (95% CI 39 to 76 percent) and five-year overall survival of 52 percent (95% CI 32 to 72 percent). By contrast, the five-year survival for patients who underwent R1 resection (microscopic positive margins) and R2 resection (macroscopic positive margins) was 11 and 0 percent, respectively [105]. Salvage resection may entail multivisceral resection in order to achieve microscopically negative margins [106]. (See 'Locally advanced cancer' above.)

Surgical management of patients with concurrent local recurrence and metastatic disease (eg, liver) should be based upon resectability of both sites and patient symptoms. Systemic therapy and management of metastatic colon cancer is reviewed elsewhere. (See "Potentially resectable colorectal cancer liver metastases: Integration of surgery and chemotherapy", section on 'Systemic chemotherapy' and "Systemic therapy for nonoperable metastatic colorectal cancer: Selecting the initial therapeutic approach" and "Systemic therapy for nonoperable metastatic colorectal cancer: Approach to later lines of systemic therapy".)

SPECIAL CONSIDERATIONS DURING THE COVID-19 PANDEMIC — The COVID-19 pandemic has increased the complexity of cancer care. Important issues include balancing the risk from delaying cancer treatment versus harm from COVID-19, minimizing the number of clinic and hospital visits to reduce exposure whenever possible, mitigating the negative impacts of social distancing on delivery of care, and appropriately and fairly allocating limited healthcare resources. Specific guidance for decision-making for cancer surgery on a disease-by-disease basis is available from the American College of Surgeons, from the Society for Surgical Oncology, and from others. These and other recommendations for cancer care during active phases of the COVID-19 pandemic are discussed separately. (See "COVID-19: Considerations in patients with cancer".)

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Colorectal cancer" and "Society guideline links: Colorectal surgery for cancer".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Colon and rectal cancer (The Basics)" and "Patient education: Colectomy (The Basics)")

●Beyond the Basics topics (see "Patient education: Colon and rectal cancer (Beyond the Basics)" and "Patient education: Colorectal cancer treatment; metastatic cancer (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●Goals for surgical resection of primary colon cancer – The majority of primary cancers arising in the colon are adenocarcinomas. Surgical resection is the only curative treatment modality for localized colon cancer. The goal of surgical resection is complete removal of the tumor, the major vascular pedicles, and the lymphatic drainage basin of the affected colonic segment. (See 'Introduction' above and 'Candidates for resection' above.)

●Preoperative evaluation – Preoperative evaluation for patients diagnosed with colon cancer typically includes history and physical examination, baseline serum carcinoembryonic antigen (CEA) level, chest/abdomen/pelvis computed tomography (CT) scan, and colonoscopy. (See 'Preoperative evaluation' above and "Clinical presentation, diagnosis, and staging of colorectal cancer", section on 'Staging'.)

●Management of malignant polyps – The majority of colorectal cancers arise from polyps (adenomas). Endoscopic management (eg, polypectomy) is sufficient for pedunculated or sessile malignant polyps that can be removed in one piece and have none of the high-risk features. Polyps with high-risk features require radical resection because of an increased incidence of residual cancer and/or lymphatic spread. (See 'Malignant polyp' above and "Overview of the management of primary colon cancer", section on 'Management of carcinoma in a polyp'.)

●Open versus laparoscopic surgery – For patients with uncomplicated localized colon cancers who have not had prior extensive abdominal surgery, we recommend laparoscopic-assisted colectomy rather than open colectomy (Grade 1B). In experienced hands, appropriately selected patients have comparable oncologic outcomes, perioperative morbidity and mortality, and faster recovery with laparoscopic as compared with open surgery. (See 'Open versus laparoscopic colectomy' above.)

●Principles of oncologic resection – Regardless of whether a laparoscopic or open colectomy is performed, the tumor-bearing colon should be removed with a proximal and a distal margin of at least 5 to 7 cm. The colonic segment should be removed en bloc with the associated mesentery to the origin of the named primary feeding vessel without any defect in the mesentery. The surgical specimen should contain at least 12 lymph nodes. If fewer than 12 lymph nodes are identified in the resected specimen, adjuvant chemotherapy may be required even without demonstrable metastatic disease in the examined nodes. (See 'Resection margins' above and 'Regional lymphadenectomy' above and "Adjuvant therapy for resected stage II colon cancer".)

●Splenic flexure cancer – While most colon cancers located at the splenic flexure may be resected with a left hemicolectomy (preservation of inferior mesenteric artery [IMA]) or extended left colectomy (ligation of IMA due to lymphadenopathy), an obstructing lesion or a suspicion for Lynch syndrome may require an extended right colectomy. Compared with a left colectomy, an extended right colectomy may achieve a more tension-free, better-vascularized anastomosis, but the patient may have more frequent bowel movements due to the loss of the ileocecal valve. There is no difference in reported oncologic outcomes. (See 'Splenic flexure' above.)

●Locally advanced cancer – For patients with locally advanced (eg, T4) tumors that involve contiguous organs or structures, we perform an en bloc multivisceral resection as needed to obtain negative resection margins of the involved structures. The plane of adherence between the colonic tumor and the adjacent organ(s) should not be disrupted, because a substantial portion of these adhesions are malignant and transection of tumor could further impair prognosis. (See 'Locally advanced cancer' above and "Overview of the management of primary colon cancer", section on 'Locally advanced primary lesions'.)

●Complicated disease – For patients with complications related to a resectable primary tumor (eg, bleeding, perforation, or obstruction), the decision to proceed with surgery needs to be individualized depending on the presenting symptoms and signs as well as the medical condition of the patient. Such patients may require a staged approach to resection. (See 'Complicated disease' above.)

●Metastatic disease – The initial management of patients who present with distant metastatic (stage IV) disease is individualized. In general, the choice and sequence of treatment is guided by the presence or absence of symptoms or complications related to the primary tumor and whether or not the metastatic lesions are potentially resectable. (See 'Metastatic disease' above.)

•Medically fit patients with a limited number of metastases in the liver and/or lung in particular are candidates for potentially curative resection of the metastases. (See "Locoregional methods for management and palliation in patients who present with stage IV colorectal cancer", section on 'Management of the primary cancer' and "Systemic therapy for metastatic colorectal cancer: General principles" and "Systemic therapy for nonoperable metastatic colorectal cancer: Selecting the initial therapeutic approach".)

•In the setting of unresectable metastatic disease, patients are managed according to the severity of the symptoms or complications relative to the primary site and the medical condition of the patient. (See 'Complicated disease' above and 'Palliative surgery' above.)

●Recurrent disease – Patients suspected of having a locoregional recurrence should undergo comprehensive restaging to determine candidacy for a salvage resection. The most important prognostic factor is the ability to achieve microscopic negative margins (R0 resection). Multivisceral resection and multidisciplinary input (eg, for chemotherapy, radiation therapy) may be required. (See 'Locoregional recurrence' above.)

ACKNOWLEDGMENT — The UpToDate editorial staff acknowledges Miguel A Rodriguez-Bigas, MD, who contributed to earlier versions of this topic review.