The levels of evidence (classes I-V) and the grades of recommendations (A-D) are defined at the end of the "Major Recommendations" field.
Preoperative Assessment
- Patients should be evaluated for their medical fitness to undergo surgery. When an ostomy is a consideration, preoperative counseling with an enterostomal therapist should be offered when available. Level of Evidence: III; Grade of Recommendation: B.
Appraisal of operative risk, especially with respect to cardiopulmonary comorbidity, is an essential part of the preoperative process. History and physical examination are the cornerstones of diagnostic evaluation and may prompt further investigation and intervention to optimize operative risk. In selected cases, a nonsurgical approach to the lesion may be necessary. Several perioperative, risk-assessment scoring systems have been published to help guide the surgeon. The need for ancillary laboratory tests is guided by history and physical examination.
- Clinical assessment should include a family history to identify patients with familial cancer syndromes and to evaluate familial risk. Level of Evidence: III; Grade of Recommendation: B.
A family medical history should be taken from patients with rectal cancer to identify close relatives with a cancer diagnosis. The clinician should look for patterns consistent with the genetic syndromes of hereditary nonpolyposis colorectal cancer, familial adenomatous polyposis, and familial colorectal cancer because this may affect surgical decisions.
The colorectal cancer risk in family members increases with the number of affected members, the closeness of the relationship to the patient, and earlier age of onset. Medical information that patients provide about their relatives often is inaccurate. If a family medical history seems to be significant but proves difficult to confirm, it may be appropriate to seek expert help from a familial cancer clinic.
- Digital rectal examination and rigid proctosigmoidoscopy are typically required for accurate tumor assessment. Level of Evidence: Class V; Grade of Recommendation: D.
Digital rectal examination enables detection and assessment of the size and degree of fixation of mid and low rectal tumors. Although digital assessment of the extent of local disease may be imprecise, it provides a rough estimate of the local staging of rectal cancer. Rigid proctosigmoidoscopy is usually performed in conjunction with the digital rectal examination. It usually allows the most precise assessment of tumor location and the distance of the lesions from the anal verge. These issues are critical in optimizing preoperative planning.
- Full colonoscopy should be performed to exclude synchronous neoplasms. Barium enema may be used for those patients unable to undergo complete colonoscopy. Level of Evidence: III; Grade of Recommendation: B.
Colonoscopy is currently the most accurate tool for screening the colon and rectum for neoplasms. The sensitivity of colonoscopy for colon cancer is typically in the range of 95 percent. Colonoscopy allows biopsy and histologic confirmation of the diagnosis. It also allows for identification and endoscopic removal of synchronous polyps.
- Computed tomography (CT) scanning of the abdomen and pelvis and transrectal ultrasound (TRUS) or magnetic resonance imaging (MRI) should typically be performed in patients who are potentially surgical candidates. Level of Evidence: III; Grade of Recommendation: B.
- Routine chest radiographs or chest CT scanning should usually be performed. Level of Evidence: III; Grade of Recommendation: B.
Rectal cancer is more likely than colon cancer to be associated with lung metastases without liver metastases. The finding of pulmonary metastases often will alter patient management decisions and therefore is warranted in most clinical situations. Abnormal findings on plain radiographs usually warrant chest CT scanning.
- Carcinoembryonic antigen (CEA) level should usually be determined preoperatively. Level of Evidence: III; Grade of Recommendation: B.
Treatment Considerations
Surgery is the mainstay of treatment for rectal cancer. The risk of recurrence is dependent on the TNM stage (See Table 1 in the original guideline document titled, "Definition of TNM"). Early stage cancer can be treated by surgical resection alone. More advanced lesions require adjuvant therapy to increase the probability of cure.
Surgical Therapy
Resection Margin
A 2-cm distal margin is adequate for most rectal cancers. Level of Evidence: Class III; Grade of Recommendation: B.
In smaller cancers of the low rectum without adverse histologic features, a 1-cm distal margin is acceptable. Level of Evidence: Class III; Grade of Recommendation: B.
Margins >1 cm should be obtained with larger tumors, especially those demonstrating adverse histologic features. The margins of resection should be measured in the fresh, pinned out specimen. The formalin-fixed specimen may shrink up to 50 percent in length.
Level of Proximal Vascular Ligation
Proximal lymphovascular ligation at the origin of the superior rectal artery is adequate for most rectal cancers. Level of Evidence: Class III; Grade of Recommendation: B.
Appropriate lymphadenectomy is based on the ligation of the major vascular trunks. There is no demonstrable survival advantage for a high ligation of the inferior mesenteric artery at its origin. Available evidence suggests that for colorectal cancer without clinically suspicious nodal disease, removal of lymphovascular vessels up to the origin of the primary feeding vessel is adequate. Thus for rectal cancer, this is at the origin of the superior rectal artery, just distal to the origin of the left colic artery. In patients with lymph nodes thought to be involved clinically, removal of all suspicious nodal disease up to the origin of inferior mesenteric artery is recommended. Suspicious periaortic nodes may be biopsied for staging purposes. High ligation of the inferior mesenteric vessels may be helpful to provide additional mobility of the left colon, as often is required for a low colorectal anastomosis or a colonic J-pouch construction.
Circumferential Resection Margin
For distal rectal cancers, total mesorectal excision (TME) is recommended. For upper rectal cancers, a tumor-specific mesorectal resection is adequate. Level of Evidence: Class II; Grade of Recommendation: A.
En Bloc Resection of Adherent (T4) Tumors
Rectal cancers with adjacent organ involvement should be treated by en bloc resection. Level of Evidence: Class III; Grade of Recommendation: B.
Inadvertent Perforation
Inadvertent perforation of the rectum worsens oncologic outcome and should be documented. Level of Evidence: Class III; Grade of Recommendation: B.
Other Operative Considerations
- Grossly normal ovaries need not be removed. Level of Evidence: Class III; Grade of Recommendation: B.
Ovarian metastases from rectal cancer occur in up to 6 percent of patients and are usually associated with widespread disease and poor prognosis. There are no data to support routine prophylactic oophorectomy. Direct invasion of the ovary is treated with an en bloc resection. Oophorectomy should be considered if the organ is grossly abnormal in postmenopausal females or in females who have received preoperative pelvic radiotherapy. Bilateral oophorectomy is indicated if only one ovary is involved, because there is a high risk of occult metastatic disease in the contralateral ovary.
- There is insufficient evidence to recommend intraoperative rectal washout. Level of Evidence: Class IV; Grade of Recommendation: C.
- Curative local excision is an appropriate treatment modality for carefully selected T1 rectal cancers. Level of Evidence: Class II; Grade of Recommendation: B.
Local excision of rectal cancer is an appropriate alternative therapy for selected cases of rectal cancer with a low likelihood of nodal metastases. This probability is dependent on the depth of tumor invasion (T stage), tumor differentiation, and lymphovascular invasion. Comparative trials to abdominoperineal resection support transanal local excision with curative intent for T1, well-differentiated cancers that are <3 cm in diameter and occupy <40 percent of the circumference of the rectal wall.
The tumor must be excised intact by full-thickness excision with clear margins. It should be orientated and pinned out for complete pathologic examination. If unfavorable features are observed on pathologic examination, a radical excision is warranted.
- Laparoscopic-assisted resection of rectal cancer is feasible but requires specific surgical expertise. Its oncologic effectiveness remains uncertain at this time. Level of Evidence: Class II; Grade of Recommendation: B.
- Emergency intervention: Primary resection of an obstructing or perforated carcinoma is recommended unless medically contraindicated. Level of Evidence: Class III; Grade of Recommendation: A.
Hemorrhage, obstruction, and bowel perforation are the most common indications for emergency intervention for rectal cancer. Appropriate management must be individualized with options, including resection with anastomosis and proximal diversion, or diversion alone followed by radiation. Other alternatives include endoluminal stenting or laser/cautery recanalization. Self-expandable metallic stents can be used to relieve obstruction by a proximal rectal cancer. This allows for mechanical bowel preparation, elective resection, and anastomosis. In some cases with advanced metastatic disease or major comorbidities, it may constitute definitive treatment.
Adjuvant Therapy
Adjuvant chemoradiation should be offered to patients with Stage II and III rectal cancers. Level of Evidence: Class I; Grade of Recommendation: A.
Definitions:
Levels of Evidence
- Meta-analysis of multiple well-designed, controlled studies, randomized trials with low false-positive and low false-negative errors (high-power)
- At least one well-designed experimental study; randomized trials with high false-positive or high false-negative errors or both (low-power)
- Well-designed, quasi-experimental studies, such as nonrandomized, controlled, single-group, preoperative-postoperative comparison, cohort, time, or matched case-control series
- Well-designed, nonexperimental studies, such as comparative and correlational descriptive and case studies
- Case reports and clinical examples
Grades of Recommendations
- Evidence of Type I or consistent findings from multiple studies of Type II, III, or IV
- Evidence of Type II, III, or IV and generally consistent findings
- Evidence of Type II, III, or IV but inconsistent findings
- Little or no systematic empirical evidence
