Huichuan Yu, Wenhao Chen, Yonghua Cai, Yanxin Luo, Liang Kang, Meijin Huang, Hui Peng and Jianping Wang
Background: It is important to predict patients with rectal cancer responding well to neoadjuvant chemoradiotherapy (nCRT). Numerous studies have yielded inconsistent results regarding the relationship between pretreatment CEA level and the response to nCRT in patients with rectal cancer. We conducted a systematic review and meta-analysis of these studies to define the relationship between them. Methods: A literature search of all major databases was performed. A total of 14 previously published eligible studies including 3,705 cases were identified and included in this meta-analysis. Results: Normal CEA (<5 ng/ml) predicted improved pathological complete response (pCR) (FE: RR 3.33; 95% CI 2.57–4.31; P<0.00001) and good response (FE: RR 1.86; 95% CI 1.08–3.21; P < 0.00001) to nCRT. Moreover, Normal CEA was significantly associated with decreased poor response (RE: RR 0.78; 95% CI 0.73–0.83; P<0.00001) to nCRT. Conclusions: The current meta-analysis suggests that pretreatment normal CEA level is a useful predictive factor for response to neoadjuvant treatment in patients with rectal cancer. The validated predictive value of pretreatment CEA on pCR should be considered in the design of further clinical studies to determine the safety and efficacy of wait-and-watch approach.