Local resection for small rectal cancer.

Rectal resection with total mesorectal excision is the standard treatment for rectal cancers. Local excision represents an alternative with less post-operative mortality and morbidity and preservation of intestinal and bladder function. However, local excision cannot provide adequate nodal staging. Presently, endorectal ultrasound and magnetic resonance imaging are used to select the appropriate patients for local excision, those with limited T1 rectal tumors. There is general agreement that the ideal tumors for local excision are less or equal to 3 cm in diameter, superficial (usTis and/or usT1N0), infra-peritoneal, located below the middle rectal valve, and involving no more than 40% of the rectal circumference. Transanal tumor excision is suitable for distal tumors and transanal endoscopic microsurgery for mid and upper lesions. The principles of adequate resection margin, non-fragmentation, and full-thickness excision are similar to those for any cancer resection. Unfavorable pathologic criteria, as assessed on the fixed rectal specimen, include depth of tumor invasion (submucosal [T1sm3] or muscular [T2]), positive resection margins, vascular and/or lymphatic invasion, and poor differentiation. Further radical surgery is required in case of unfavorable criteria. Simple surveillance may be advised for superficial tumors (T1sm1) without any unfavorable criteria. Management of T1sm2 tumors without any unfavorable criteria should be discussed on a case-by-case basis.