Adjuvant chemotherapy for rectal cancer with complete pathological response (pCR) may not be necessary: a pooled analysis of 5491 patients

BACKGROUND: It is recommended postoperative adjuvant chemotherapy for all rectal cancers undergoing neo-chemoradiotherapy regardless of the final yield pathology. However, the role of adjuvant chemotherapy in pathological complete response (pCR) remains controversial. We aimed to identify the necessarily of adjuvant chemotherapy in pCR. METHODS: Consecutive patients with pCR in Fudan University Shanghai Cancer Center (FUSCC) were enrolled. Meanwhile, a pooled analysis of individual patient with pCR was performed from PubMed and Embase databases for validation. RESULTS: A total of 171 patients form FUSCC were identified to achieve pCR with up to almost 10 years follow-up. Among them, those receiving adjuvant chemotherapy had no survival benefits compared to those without adjuvant chemotherapy (log-rank test = 0.17, P = 0.676). The 5y-DFS rates for patients in chemo group and no-chemo group was 87.5 and 88.8%, respectively, showing no significant difference (p = 0.854). No matter chemotherapy regimens, T stage, EMVI and CRM status varied, the results remained consistent. Meantime, the COX model did not demonstrate adjuvant chemotherapy as the independent risk factor for OS and DFS. Additionally, among 18 systemic recurrences in all, the rate of relapse surged rapidly on the 12 months and rose up to peak in the 36th months. In order to validate these results, nine controlled trials involving 5491 patients with pCR were included in this pooled-analysis. For both 5-year overall survival and disease-free survival, the pooling data did not produce a statistically significant effect in cases of adjuvant chemotherapy performed (RR = 0.79 and RR = 0.95, respectively, all p > 0.05). CONCLUSION: This study suggested that rectal cancer patients with pCR did not benefit from adjuvant chemotherapy and we recommended that achievement of pCR require more prolonged close follow care in case of distant metastasis.