BackgroundIn the current NCCN guidelines, the prognosis and adjuvant chemotherapy of patients who underwent neoadjuvant chemoradiotherapy (nCRT) are based on pre-radiotherapy clinical TNM (cTNM) stage. However, the value of neoadjuvant pathologic TNM (ypTNM) stage is not clearly described.MethodsThis retrospective study investigated the prognosis and adjuvant chemotherapy which based on ypTNM stage compared to cTNM stage. Between 2010 and 2015, a total of 316 rectal cancer patients who underwent nCRT, followed by total mesorectal excision (TME), were included for analysis.ResultsOur findings revealed that cTNM stage was the only significant independent factor in the pCR group (HR = 6.917, 95% CI: 1.133–42.216,P= 0.038). In the non-pCR group, ypTNM stage was more important than cTNM stage in prognosis (HR = 2.704, 95% CI: 1.811–4.038,P< 0.001). In ypTNM III stage group, there was a statistically significant difference in prognosis between the patients with and without adjuvant chemotherapy (HR = 1.943, 95% CI: 1.015–3.722,P= 0.040), but there was no significant difference in cTNM III stage group (HR = 1.430, 95% CI: 0.728–2.806,P= 0.294).ConclusionsWe concluded that ypTNM stage, rather than cTNM stage, might be a more important factor in the prognosis and adjuvant chemotherapy of patients with rectal cancer who underwent nCRT.