Is adjuvant chemotherapy necessary for patients with pathological complete response after neoadjuvant chemoradiotherapy and radical surgery in locally advanced rectal cancer? Long-term analysis of 40 ypCR patients at a single center

According to practice guidelines, adjuvant chemotherapy (ACT) is required for all patients with locally advanced rectal cancer who have received neoadjuvant chemoradiotherapy (NCRT) and total mesorectal excision (TME). The objective of this study was to determine whether ACT is necessary for patients achieving pathological complete response (pCR) after NCRT followed by surgery. By retrospectively reviewing a prospectively collected database in our single tertiary care center, 210 patients with locally advanced rectal cancer who underwent NCRT followed by TME were identified between February 2005 and August 2013. All patients achieving ypCR were enrolled in this study, in which who underwent ACT (chemo group) and who did not (non-chemo group) were compared in terms of local recurrence (LR) rate, 5-year disease-free survival (DFS) rate and overall survival (OS) rate. Forty consecutive patients with ypCR were enrolled, 19 (47.5 %) in chemo group and 21 (52.5 %) in non-chemo group. After a median follow-up of 57 months, five patients developed systemic recurrences, with the 5y-DFS rate of 83.5 %. No LR occurred in the two groups. The 5y-DFS rates for patients in chemo group and non-chemo group was 90.9 and 76.0 %, respectively, showing no statistically significant difference (p = 0.142). Multivariate analysis showed that tumor grade was the only independent prognostic factor for 5y-DFS and 5y-OS. Results of this study suggested that it may not be necessary for all rectal cancer patients with ypCR after NCRT and radical surgery to receive ACT. Prospective randomized trials are warranted to further determine the value of ACT for ypCR patients.