Is adjuvant chemotherapy necessary for patients with ypT0–2N0 rectal cancer treated with neoadjuvant chemoradiotherapy and curative surgery?

BACKGROUND AND OBJECTIVE: The benefit from adjuvant chemotherapy for patients treated with neoadjuvant chemoradiotherapy (NCRT) and curative surgery remains controversial, particularly among those responding well to NCRT. This retrospective study aimed to clarify the benefits of adjuvant chemotherapy in terms of the oncological outcomes of patients with ypT0–2N0 rectal cancer after NCRT and curative surgery. METHODS: All patients with ypT0–2N0 rectal cancer after NCRT and curative resection between 2005 and 2014 were examined. The oncological outcomes between patients treated with adjuvant chemotherapy and those without any chemotherapy were compared. RESULTS: The clinicopathological characteristics of 110 patients were reviewed in this study; one patient was excluded due to lack of follow-up. Of the 109 patients included, 58 (53.2%) underwent adjuvant chemotherapy (chemo group), whereas the remaining 51 (46.8%) did not receive any chemotherapy (non-chemo group). After a median follow-up of 50 months, there were no significant differences in the 5-year overall survival (OS) or recurrence-free survival (RFS) rates between the groups (OS: 92.1 vs 86.3%, P = 0.375; RFS: 80.9 vs 74.7%, P = 0.534). Subgroup analysis also demonstrated no significant differences in 5-year OS and RFS rates between patients with ypT0N0 rectal cancer (P = 0.712 and P = 0.599, respectively) and those with ypT1–2N0 disease (P = 0.255 and P = 0.278, respectively). CONCLUSIONS: These results indicate that patients with ypT0–2N0 rectal cancer after NCRT followed by curative surgery may not derive significant benefit from adjuvant chemotherapy. However, further prospective randomized trials, with larger sample sizes, are warranted to confirm this conclusion.