There are three potential options for surgical resection in stage I rectal cancer: local excision, LAR, and APR. Local excision should be restricted to tumors confined to the rectal wall and that do not, on rectal ultrasound or magnetic resonance imaging, involve the full thickness of the rectum (i.e., not a T3 tumor). The ideal candidate for local excision has a T1 tumor with well-to-moderate differentiation that occupies less than one-third of the circumference of the bowel wall. Local excision should only be applied to very select patients with T2 tumors, as there is a higher risk of local and systemic failure.
For patients with T1 and T2 tumors, no randomized trials are available to compare local excision with or without postoperative chemoradiation to wide surgical resection (LAR and APR). Investigators with the Cancer and Leukemia Group B (CALGB) enrolled patients with T1 and T2 rectal adenocarcinomas that were within 10 cm of the dentate line and not more than 4 cm in diameter, and involving not more than 40% of the rectal circumference, onto a prospective protocol, CLB-8984. Patients with T1 tumors received no additional treatment following surgery, whereas patients with T2 tumors were treated with EBRT (54 Gy of 30 fractions, 5 days/week) and 5-FU (500 mg/m2 on days 1 through 2 and days 29 through 31 of radiation). At 48 months median follow-up, the 6-year failure-free survival and overall survival (OS) rates for patients with T1 tumors were 83% and 87%, respectively. For patients with T2 tumors, the 6-year failure-free survival and OS rates were 71% and 85%, respectively.