Abstract 3197: Serum CEA change predicts tumor regression and prognosis in locally advanced rectal cancer

Abstract

Abstract Objective: To investigate the value of carcinoembryonic antigen (CEA) change in predicting pathological tumor regression and outcome for locally advanced rectal cancer (LARC) patients received neoadjuvant therapy. Material and methods: LARC patients who received neoadjuvant therapy and radical tumor resection were retrospectively collected. The predictive value of baseline CEA, post-treatment CEA and post/pre-treatment CEA ratio for tumor regression grade (TRG), overall survival and diseases free survival were estimated by logistic regression or cox proportional hazard regression. Results: 700 LARC patients were enrolled in the study with 475 (67.9%) cases of male patients and median age of 56 (20-87). Of the all patients enrolled, multivariate analysis showed post-treatment CEA (OR=1.142, 95% CI: 1.073-1.215, P<0.001) was an independent predictor for TRG. 284 patients with elevated baseline CEA were analyzed. Among them, 168 patients (59.2%) have normalized CEA. Multivariate analysis showed post-treatment CEA (OR=1.068, 95% CI: 1.007-1.133, P=0.027), CEA ratio (OR=3.463, 95% CI: 1.269-9.446, P=0.015) were independent predictors for TRG(Table 1). Of the all patients enrolled, multivariate analysis showed low preoperative albumin level (HR=0.919, 95% CI: 0.886-0.952, P<0.001), tumor deposit (HR=3.226, 95% CI: 1.470-7.077, P=0.003), nerve infiltration (HR=3.602, 95% CI: 1.736-7.476, P=0.001), high post-treatment CEA (HR=1.029, 95% CI: 1.010-1.049, P=0.003) were independent unfavored predictors for overall survival of LARC patients. 700 patients were divided into 3 groups: A group with normal baseline CEA (n=416,59.4%); B group with normalized CEA (n=168,24.0%); C group with elevated baseline and post-treatment CEA (n=116,16.6%). The overall survival and disease free survival of group B were comparable to that of group A (P=0.588,0.053) and significantly better than that of group C (B vs. C: P=0.010, 0.003; A vs. C: P=0.007, <0.001). Conclusion: 1. Post-treatment CEA is an independent predictor for TRG of LARC patients and higher post-treatment CEA precdicted poor overall survival. 2. Post/pre-treatment CEA ratio is an independent predictor for TRG of LARC patients with elevated baseline CEA. Citation Format: Zerong Cai, Lingyu Huang, Ping Lan, Xiaojian Wu. Serum CEA change predicts tumor regression and prognosis in locally advanced rectal cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3197.