Is adjuvant chemotherapy necessary for rectal cancer patients staged at ypT3-4N0?

Abstract

Abstract Purpose: There is substantial evidence evaluating the clinical efficacy of adjuvant chemotherapy (AC) for rectal cancer patients staged at ypN+ and ypT0-2N0, but few studies focus on those staged at ypT3-4N0. Methods: Data were collected from the Surveillance, Epidemiology and End Results (SEER) database from January 2011 to December 2015. Stabilized inverse probability of treatment weighting (sIPTW) was adopted to balance the baseline clinicopathological characteristics of ypT3-4N0 patients receiving AC or not. A risk score was established to predict the prognosis in terms of overall survival (OS) and identify who would be the beneficiary of AC. Results: A total of 920 patients staged at ypT3-4N0 were eligible, including 311 patients (33.8%) receiving AC. No significant difference was observed in OS between patients receiving AC or not before and after sIPTW (both P>0.05). The current risk score exhibited better discrimination power and overall net benefit than the 8th AJCC staging system, as well as improved prediction power. Based on the risk score, patients were divided into high- and low-risk subgroups, and only the high-risk subgroup was found to benefit from AC (P<0.05). Lastly, the risk score was validated by 100 consecutive patients from Fujian Cancer Hospital, and the advantage of AC was also confirmed in the high-risk subgroup. Conclusion: In this study, we proposed a risk-adapted and readily accessible risk score to guide the management of AC in ypT3-4N0 patients. According to the risk score, high-risk patients should be routinely recommended AC.