Evaluation of treatment response and tissue necrosis as prognostic indicators following neoadjuvant chemoradiotherapy in rectal cancer patients

BACKGROUND/AIMS The objective of this study was to assess the prognostic roles of treatment response and tissue necrosis after chemoradiotherapy (CRT) in locally advanced rectal cancer. METHODS A total of 243 patients with locally advanced rectal cancer who underwent neoadjuvant CRT were included. Three treatment response groups were classified by their pathological stage results: complete treatment response (CTR), intermediate treatment response (ITR), and poor treatment response (PTR). Three tissue necrosis groups were classified based on tissue pathological results: complete necrosis response (CNR), intermediate necrosis response (INR), and poor necrosis response (PNR). RESULTS Overall survival (OS) and recurrence-free survival (RFS) rate at three years were 74.5% and 61.3%, respectively. The 3-year OS rates of the CTR, ITR, and PTR groups were 83.7%, 75.9%, and 69.7%, respectively (p < 0.001); the 3-year RFS rates were 76.7%, 69.0%, and 52.1%, respectively (p < 0.001). The 3-year OS rates of the CNR, INR, and PNR groups were 83.7%, 80.6%, and 61.8%, respectively (p < 0.001); the 3-year RFS rates were 76.7%, 68.9%, and 44.3%, respectively (p < 0.001). When compared to CTR/CNR, PTR/PNR was strongly related to an increased risk of recurrence (hazard ratio [HR], 5.53; 95% confidence interval [CI], 2.01 to 15.23 vs. HR, 6.37; 95% CI, 2.29 to 17.74, respectively) in univariate Cox regression. Both PTR and PNR were strongly associated with shorter RFS and OS when compared with CTR and CNR in the multivariate Cox regression. CONCLUSIONS Tissue necrosis is an equally important prognostic marker as treatment response for oncologic outcomes in locally advanced rectal cancer.