Change in carbohydrate antigen 19-9 level as a prognostic marker of overall survival in locally advanced pancreatic cancer treated with concurrent chemoradiotherapy

Purpose To investigate the significance of carbohydrate antigen 19-9 (CA19-9) levels for survival in locally advanced pancreatic cancer (LAPC) treated with concurrent chemoradiotherapy (CCRT). Methods/patients We retrospectively reviewed data from 97 LAPC patients treated with CCRT between 2000 and 2013. CA19-9 levels (initial and post-CCRT) and their changes [{(post-CCRT CA19-9 level - initial CA19-9 level)/(initial CA19-9 level)} x 100] were analyzed for overall survival. A cut-off point of 37 U/mL was used to analyze initial and post-CCRT CA19-9 levels. In order to define an optimal cut-off point for change in CA19-9 level, the maxstat package of R was applied. Results Median overall survival was 14.7 months (95% CI 13.4-16.0), and the 2-year survival rate was 16.5%. The estimated optimal cut-off point of CA19-9 level change was 94.4%. On univariate analyses, CA19-9 level change between initial and post-CCRT was significantly correlated with overall survival (median survival time 9.7 vs 16.3 months, p < 0.001). Multivariate analyses confirmed that CA19-9 level change from initial to post-CCRT was the only prognostic factor (p < 0.001). Conclusions Change in CA19-9 level between initial and post-CCRT was a significant prognostic marker for overall survival in LAPC treated with CCRT. A CA19-9 level increase > 94.4% might serve as a surrogate marker for poor survival in patients with LAPC undergoing CCRT, and the prognostic power surpassed other CA19-9 variables including initial and post-CCRT values.