Introduction

Surgery remains the primary modality of treatment for malignancies of the lower gastrointestinal tract. Based on experience, an estimated 90% to 92% of patients with colon cancer and 84% of patients with rectal cancer are treated surgically. The chance of cure with surgery as the sole treatment modality decreases with increasing tumor depth penetration and lymph node involvement.¹ Variations in surgical techniques exist in the treatment of colorectal cancer and can be best evaluated by studying rates of local recurrence and survival. The wide range in recurrence rate (4%–55%) is evidence that the type of surgical technique significantly affects cancer outcome, especially for rectal cancer. Based on the latter findings, the National Cancer Institute ([NCI] Bethesda, Maryland) systematically reviewed the literature and drafted guidelines to reduce surgical variation and to help standardize documentation. These guidelines helped minimize inconsistencies in staging patients with colorectal cancer and enhanced surgical quality control in 2001. Along with the surgical principles governing them, these guidelines are incorporated into the remainder of this chapter.

Surgical Oncologic Principles: Historical Perspective

In the 1960s, the idea that modifying surgical techniques to consider oncologic principles can have a positive influence on survival in colorectal cancer began to formulate. Turnball and associates,² in a much-criticized study in 1967 at the Cleveland Clinic Hospital, retrospectively compared the outcomes of patients who had resections for malignancy using the no-touch isolation technique with the outcomes of patients who underwent more traditional resections. The no-touch isolation technique involves the ligation of the draining vessels at their origin early in the dissection, then the proximal and distal bowel to the lesion is ligated, and finally the tumor is mobilized. This procedure isolates the tumor, which prevents intraluminal and hematogenous spillage that would otherwise occur during manipulation of the tumor. The study concluded that patients with no-touch oncologic resection had a better 5-year survival rate.

In 1998, Wiggers and associates ³ compared the no-touch technique with the conventional technique in a randomized prospective trial. The trial found no significant difference in 5-year survival rates between the no-touch group and the conventional group, but there was a trend toward better cancer-related survival in the former group. The trials emphasized the fact that operative techniques and following oncologic principles are essential; however, the no-touch technique is no longer followed. Since then, evidence increasingly suggests that the quality of the oncologic outcome is directly proportional to the surgical team’s adherence to NCI oncologic guidelines. Most of the evidence comes from rectal cancer, but the correlation holds for colon cancer. The German Study Group Colo-Rectal Carcinoma trial showed that the surgeon is a critical variable in determining locoregional recurrence rate and morbidity.⁴

The oncologic principles involving resection include:

High ligation of all draining mesenteric vessels

Minimal trauma during mobilization

Adequate margins

Clearance of tumors from invading organs

Complete intraoperative exploration

Oncologic Principles for Bowel Resection and Margins

Operative planning for resection for colonic malignancy ideally should include radical en bloc removal of the blood supply and the draining of lymphatics at the level of the origin of the primary feeding arterial vessel. The vascular supply to the colon is demonstrated in Figure 14-1. The ultimate length of the resected bowel segment is dictated by the lymphovascular resection. Enker and associates⁵ recommend that resection of the distal and proximal margin should be at least 5 cm from the tumor, since the local recurrence rate is 6.9% for margins greater than 5 cm and 20% for those less than 5 cm in Dukes stage B. The bowel margins should be wide enough to limit intraluminal and pericolic recurrence. Generally accepted surgical principles recommend resection margin distance of 5 to 10 cm.

Figure 14-1 Lymph node and blood supply of colon and rectum.

(From Greene FL, Page DL: AJCC Cancer Staging Manual, 6th ed. Philadelphia: Lippincott Williams & Wilkins, 2002, p 123.)

Guidelines in the United States recommend ligation of the primary feeding artery at the level of its origin. Although the level of ligation of the primary feeding artery is still under debate, high ligation is favored based on results of studies that show improvement of 5-year survival rates with high versus low ligation. The following studies showed favorable 5-year survival rates with high ligation—all found in the article by Hida and colleagues ⁶: Rosi and colleagues showed 77% versus 63% with low ligation, Bacon and colleagues found 73.6% versus 63.2%, and Slanetz and Grimson found 74.5% versus 65.8%. It is recommended that when the primary tumor is equidistant from two feeding vessels, both vessels should be excised at their origin.⁶

The drainage of the lymphatic system mirrors that of the vascular system. In colon carcinoma, there are two possible directions for lymphatic drainage: central along the mesenteric vessels and para-intestinal. Divide the major draining mesenteric vessel(s) at the point of origin with the accompanying lymphatic network to prevent regional lymphatic recurrence. For right colon resections, the length of ileum resected does not appear to affect local recurrence. Therefore, the shortest length of ileum should be resected to prevent malabsorption syndromes while ensuring adequate blood supply to the anastomosis.

Staging the Extent of Cancer Resection

The extent of tumor not resected intraoperatively strongly influences prognosis and therapy. The absence or presence of residual tumor after surgical treatment is described by the letter R. Accepted guidelines from the American Joint Committee on Cancer (AJCC) Prognostic Factors Consensus Conference were recommended to describe the extent of resection. Resections should be categorized as follows:

R0—All gross disease resected by en bloc resection with margins histologically free of disease

R1—All gross disease resected by en bloc resection with margins histologically positive for disease

R2—Residual gross disease remains unresected

The radial margins should be tumor-free and histologically free of disease for the resection to be considered curative. Patients who do not have histologic assessment of radial tumor margin or who had an R1 or R2 resection are considered to have an incomplete resection for cure. Incomplete resection R1 and R2 does not change the TNM stage, but it does affect curability. This is well seen in rectal cancer when the local recurrence rate after resection of a rectal cancer was approaching 80% in those with margins positive for disease and less than 10% in those with margins negative for disease.

Lymphadenectomy

Lymph node resection carries prognostic and therapeutic implications. The lymph node resection should be radical and removed en bloc. The lymph node dissection should be carried to the level of the origin of the primary feeding vessel. Colon cancer staging requires adequate analysis of lymph nodes to determine prognosis and further treatment. The 1990 Working Party report of the World Congress of Gastroenterology recommends that at least 12 lymph nodes must be evaluated. This recommendation was reiterated by an NCI sponsor panel of experts.⁷

A systemic review of evidence for the association between lymph node evaluation and surgical outcome in patients with colon cancer showed that the number of lymph nodes evaluated after surgical resection was positively associated with survival of patients with stage II and stage III colon cancer.⁸ Because of the high risk for recurrence of colon cancer, adjuvant chemotherapy is recommended for patients with lymph node metastases (stage III).

However, a population-based study by Baxter and associates ⁹ found that only 37% of patients with colon cancer receive adequate lymph node evaluation during colon cancer staging. The two potentially modifiable influences are the completeness of lymph node evaluation by the examining pathologist and the adequacy of the surgical resection. The number of lymph nodes recovered has been identified as a potentially important measure of the quality of cancer care by many organizations. The proficiency of the surgeon and total hospital case volume are positively associated with the number of lymph nodes recovered. Patients in lower-volume hospitals were more likely to have fewer than seven lymph nodes detected. The experience of the pathologist and the technique of pathologic evaluation have also been shown to be important in lymph node recovery after adjusting for surgeon and tumor-related factors.

Guidelines in the United States recommend that nodes at the origin of the primary feeding artery (apical node) should be tagged for pathologic evaluation because the apical nodes have prognostic significance in addition to the number of nodes positive for disease in the specimens. The apical lymph node is defined as the “most proximal lymph node within 1 cm of vessel ligation at apex of vascular pedicle.”^6,^7,¹⁰ Multivariate analysis has shown that involvement of the apical lymph node is significantly associated with adverse outcome. The general recommendation for surgical resection of the colon is to ligate the primary feeding arterial vessel at the level of its origin and resect at least 5 cm of bowel on both sides. This technique should produce better patient prognosis and more accurate staging. A smaller extent of resection decreases the number of recovered nodes and increases the risk of under-staging.^11,¹²

The concept of sentinel lymph node examination has been studied for colon cancer, but there is no uniformity in the definition of cellular burden, nor is there common agreement on how to clinically define relevant metastatic disease. Some studies have shown that the detection of immunohistochemistry (IHC) cytokeratin-positive cells in stage II (N0) colon cancer indicates a worse prognosis, whereas other studies have failed to show a survival difference. Until the use of sentinel lymph nodes and the detection of cancer cells by immunohistochemistry have been standardized and proved more effective than nodal dissection, the procedures recommended herein should be used.^13,¹⁴

Colon

Surgical Preparation

Intraoperative identification of the tumor may be difficult in patients who have small or flat tumors or who are undergoing resection after a polypectomy. This is especially true with laparoscopic procedures, in which the bowel often cannot be palpated. Preoperative localization with marking during endoscopy can assist in intraoperative identification of the tumor. If the lesion is in the cecum, the ileocecal valve and the appendiceal orifice should be viewed endoscopically; then the localization of the tumor is simple. Distal lesion can be measured from the anus; however, estimates of the location of the tumor may be inaccurate.

In our practice, endoscopic tattooing, a process in which an agent is injected into the bowel wall submucosally at or near the site of the lesion, has been used to facilitate intraoperative identification of the tumor site. The most common agent for achieving this goal is India ink, which generally yields excellent results. As an alternative, many institutions use a commercially available sterile suspension of carbon particles, which is also very safe and effective. Intraoperative endoscopy is another option for locating lesions and to confirm small tumors.

Be thorough during the endoscopy to locate all lesions. The rate of synchronous colon cancers ranges from 2% to 11%, and the incidence of synchronous adenomatous polyps may be greater than 30%. In this case, as much colon length as possible should be preserved without compromise to the cancer resection. An alternative is subtotal colectomy with an ileorectal or ileosigmoid anastomosis rather than a multiple anastomosis.¹⁵

Extent of Resection

Right Colon

Right colon cancers account for up to 15% of primary colorectal cancers. Patients with adenocarcinoma involving the cecum or ascending colon who do not have hereditary nonpolyposis colorectal cancer (HNPCC) or other synchronous lesions should be treated with a right hemicolectomy. The standard extent of resection for various colon cancers has been defined. The ileocolic, right colic, and right branch of the middle colic arteries and veins should be ligated near their origin to ensure an adequate lymphadenectomy. For tumors of the cecum and the ascending colon, a right hemicolectomy that includes the right branch of the middle colic artery at its origin should be performed. For tumors of the hepatic flexure, an extended right colectomy that includes the entire middle colic artery is indicated (Fig. 14-2).

Figure 14-2 Operative strategies for colorectal cancer by location of tumor. A, Cecal or ascending colon cancer. B, Proximal transverse colon cancer. C, Sigmoid colon cancer. D, Splenic flexure colon cancer.

(From Weiser MR, Posner MC, et al: Adenocarcinoma of the colon and rectum. In Yeo CJ [ed]: Shackelford’s Surgery of the Alimentary Tract, 6th ed. Philadelphia: Elsevier, 2007, Fig 156–6.)

(From Cohen AM: Operation for colorectal cancer: low anterior resection. In Yeo CJ [ed]: Shackelford’s Surgery of the Alimentary Tract, 6th ed. Philadelphia: Elsevier, 2007, Fig 158-1.)

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