Significance of ypTNM stage in determining the prognosis and therapy after surgery for locally advanced rectal cancer

BACKGROUND: In 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. METHODS: This 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. RESULTS: Our 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). CONCLUSIONS: We 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.