Is adjuvant chemotherapy really needed after curative surgery for rectal cancer patients who are node-negative after neoadjuvant chemoradiotherapy?

Purpose: Adjuvant chemotherapy is currently offered, as standard, after curative resection for patients with rectal cancer who receive neoadjuvant chemoradiation (NCRT). We postulate that adjuvant chemotherapy adds minimal oncologic benefit for patients who undergo total mesorectal excision who are node-negative after neoadjuvant chemoradiation.

Methods: From a prospective, institutional cancer database, rectal cancer patients who completed neoadjuvant chemoradiation and curative surgery (2000-2008) and were node-negative on final pathology were identified. Patient, tumor, treatment characteristics, and oncologic outcomes were compared for patients who completed intended adjuvant chemotherapy (group chemo) or did not receive any chemotherapy (group no-chemo).

Results: Chemo (n=58) and no-chemo (n=70) patients had similar age (P=0.13), gender (P=0.67), body mass index (P=0.46), American Society of Anesthesiologists class (P=0.67), preoperative tumor stage (P=0.16), type of surgery (P=0.76), and postoperative complications. The no-chemo group had greater complete pathologic response (n=34, 48.6% vs. n=14, 24.1%). After prolonged follow-up, local recurrence (P=1), disease-free survival (P=0.41), and overall survival (P=0.52) were similar. Oncologic benefits of adjuvant chemotherapy were especially questionable for patients with complete pathologic response (chemo vs. no-chemo, local recurrence at 5 years: 0 vs. 2.9%, P>0.99), disease-free (79.1% vs. 88%, P=0.51), and overall survival (90.9% vs. 95.2%, P=0.41).

Conclusions: These results question the routine use of adjuvant chemotherapy for patients with rectal cancer who undergo curative surgery who have been rendered node-negative by neoadjuvant chemoradiation.