Surgical Management of Cancer of the Colon

Introduction

Surgical resection is the primary curative treatment for patients with localized colorectal cancer. The most accurate prognostic indicator of colon cancer is its stage at diagnosis, and in patients with locally advanced disease, chemotherapy has a role in decreasing the risk for recurrence or metastasis.

Staging of colorectal cancer is based on the depth of penetration of the tumor into the bowel wall, the involvement of regional lymph nodes, the involvement of adjacent organs, and the presence or absence of distant metastasis. Surgery performed according to oncologic principles is designed to resect the cancer with clear margins, provide the most accurate staging possible, and preserve function. The purpose of this chapter is to describe these surgical techniques as applied to cancer of the colon.

Epidemiology

Colorectal cancer is the third most frequently diagnosed cancer in men and women and the second leading cause of cancer death in the United States. In 2013, there were an estimated 102,480 new cases of colon cancer and 40,340 new cases of rectal cancer, with an estimated 5830 deaths from colon and rectal cancers combined. However, mortality from colorectal cancer has decreased by almost 35% from 1990 to 2007, likely because of earlier diagnosis through screening and improvements in management.

Preoperative Evaluation

Preoperative assessment of the patient with colon cancer should include staging, an assessment of operative risk, and a thorough family history that documents colorectal cancer and extracolonic cancers associated with syndromes of inherited colorectal cancer. The overall physiologic status of the patient is assessed with preoperative laboratory studies such as a complete blood cell count, urinalysis, chemistry panel, electrocardiogram, and chest radiograph. Nutritional status is assessed clinically. Scoring systems that combine physical activity, symptoms, and laboratory results to assess perioperative risk have been described, including that of the American Society of Anesthesiologists and the Physiological and Operative Severity Score for the enUmeration of Mortality and morbidity (POSSUM) and the Portsmouth (p)-POSSUM scores.

A complete staging workup includes a total colonoscopy with biopsy (with consideration given to immunohistochemistry to detect mismatch repair gene expression and/or microsatellite instability testing to detect mismatch repair dysfunction that might suggest Lynch syndrome), carcinoembryonic antigen (CEA), and baseline computed tomography (CT) scans of the chest, abdomen, and pelvis. If questionable abnormalities are seen on the CT or magnetic resonance imaging (MRI) scan, a positron emission tomography/CT scan may be considered to further delineate the abnormality, particularly if more definitive information will change management.

Accurate localization of the tumor is important, especially if the cancer is small and the operation will be performed using the laparoscopic technique. Ideally, the referring colonoscopist has tattooed the colon near the tumor. An accurate family history and the results of preoperative tumor immunohistochemistry/microsatellite instability testing are important in deciding the extent of the resection.

Preoperative Preparation

The role of mechanical bowel preparation remains controversial; however, most surgeons continue to recommend bowel preparation prior to a routine colectomy. One potential benefit is to decrease the weight and distension of the colon for minimally invasive mobilization. The use of prophylactic oral antibiotics during mechanical preparation is also controversial. A recent evaluation of 24 hospitals in the Michigan Surgical Quality Collaborative Colectomy Best Practices Study showed that mechanical preparation was used in 86% of patients and that the addition of oral antibiotics reduced the risk for surgical site infections (4.5% vs 11.8%, P = .0001) and the risk for prolonged ileus (3.9% vs 8.6%, P = .011) without increasing the risk for Clostridium difficile colitis. Evidence consistently supports the use of intravenous antibiotics prior to making an incision to reduce the rate of wound infections.

Prophylaxis against deep venous thrombosis should be performed prior to the induction of anesthesia and may include subcutaneous heparin or one of the low molecular weight heparin agents. In addition, graded lower extremity compression stockings and sequential pneumatic compression devices also should be applied intraoperatively and their use should be continued postoperatively until the patient is walking.

Operative Principles and Techniques

Surgery is the primary treatment of localized colon cancer and in many cases will be the only treatment that is necessary. The surgical principles for resectable, nonmetastatic colon cancer include colectomy with complete, en bloc removal of regional lymph nodes following the principles of oncologic resection. These principles are:

• 1.

  Resection of the cancer-containing bowel and the wedge of mesentery associated with the arterial supply of the affected segment, including the regional lymph nodes

• 2.

  Ligation of the feeding vessel at its origin

• 3.

  Removal or biopsy of suspicious lymph nodes that are located outside the field of resection

• 4.

  Unresected positive lymph nodes indicate an incomplete resection

• 5.

  Minimum proximal and distal resection margins are 5 cm

• 6.

  A minimum of 12 mesenteric lymph nodes should be found and examined for accurate staging

No specific margin is recommended for clearance of the terminal ileum for patients with right colon cancer undergoing resection other than that defined by vascular supply because mural spread to the ileum is rare.