Purpose: Preoperative chemoradiotherapy followed by radical surgical resection has been the preferred treatment for patients presenting with locally advanced distal rectal carcinoma at our institutions. We postulated that chemoradiotherapy-induced pathologic response of the primary tumor would identify which patients would be candidates for local excision as definitive surgical therapy.

Methods: A retrospective analysis of 60 patients with palpable, locally advanced, distal rectal adenocarcinomas treated from 1995 to 2000 was performed. All patients received preoperative chemoradiotherapy consisting of 5-fluorouracil (325 mg/m(2)) and leucovorin (20 mg/m(2)) by bolus infusion on Days 1 through 5 and 29 through 33 delivered concurrently with at least 45.0 to 50.4 Gy of pelvic radiation, followed six to eight weeks later by radical surgery and then adjuvant chemotherapy.

Results: Among 60 patients (20 females) there was a mean age of 58.7 (28-84) years. Clinical staging was as follows: Stage II, 14 patients (23 percent); Stage III, 35 patients (58 percent); and Stage IV, 11 patients (18 percent). Pathologic examination revealed that negative margins were obtained in 58 patients (97 percent). Downstaging to T0-2N0 was achieved in 17 patients (28 percent), with five (8 percent) achieving a pathologically complete response. Lymph nodes were positive in 24 patients (40 percent) despite chemoradiotherapy. Pathologic node positivity was found in 0 of 5 pT0 patients, 9 (41 percent) of 22 pT1 or pT2, and 15 (45 percent) of 33 pT3. Clinical stage, tumor size, pathologic stage, and adverse histologic features could not reliably predict pN0 status, except pT0 (5 patients only).

Conclusions: Preoperative chemoradiotherapy often downsizes and downstages locally advanced rectal carcinoma. Neither pretreatment clinical characteristics, response to preoperative chemoradiotherapy, or pathologic features reliably predict pN0 status. Therefore, local excision is not recommended as an alternative to radical surgery for locally advanced adenocarcinoma of the distal rectum regardless of the response of the primary tumor to preoperative chemoradiotherapy.