Predictive factors for pathologic complete response after neoadjuvant chemoradiotherapy for locally advanced rectal cancer

Objective To evaluate the predictive factors associated with pathological complete response (pCR) after preoperative neoadjuvant chemoradiotherapy for rectal cancer. Methods A retrospective analysis was performed on the clinical data of 84 patients with rectal cancer, who underwent neoadjuvant chemoradiotherapy followed by radical surgery from January 2010 to December 2016. Univariate analysis and multivariate Logistic regression analysis were performed to analyze associated factors of pCR. Results In 84 patients, 18 (21.4%) achieved pCR after neoadjuvant chemoradiotherapy. The univariate analysis showed that circumferential extent of the tumor (≤1/2 cycle) (P=0.008), pre-chemoradiotherapy serum carcino embryonie antigen (CEA) level (≤5 μg/L) (P=0.001), pre-chemoradiotherapy T stage (cT1-3) (P=0.001), pre-chemoradiotherapy N stage (N0) (P=0.049), distance between tumor and the anal verge (≤5 cm) (P=0.023) were associated with pCR or non-pCR after neoadjuvant chemoradiotherapy for rectal cancer. The multivariate Logistic analysis revealed that circumferential extent of the tumor (≤1/2 cycle) (P=0.041), pre-chemoradiotherapy serum CEA level (P=0.012), and T stage (P=0.003) were predictive factors for pCR or non-pCR after neoadjuvant chemoradiotherapy for rectal cancer. Conclusion Patients with circumferential extent of the tumor (≤1/2 cycle), low CEA level, and early T stage before treatment are more likely to achieve pCR after neoadjuvant chemoradiotherapy for rectal cancer. Key words: Rectal cancer; Neoadjuvant chemoradiotherapy; Pathological features