Post-adjuvant chemotherapy CA19-9 levels predict prognosis in patients with pancreatic ductal adenocarcinoma: A retrospective cohort study.

BACKGROUND: Carbohydrate antigen 19-9 (CA19-9) is a widely used tumor marker for pancreatic ductal adenocarcinoma (PDAC). In addition, several studies have reported the utility of both pre- and postoperative CA19-9 levels as prognostic factors in resectable PDAC. However, little is known about the implications of post-adjuvant chemotherapy (AC) CA19-9 levels. The purpose of this study was to examine the utility of the post-AC CA19-9 level as a prognostic marker for relapse-free survival (RFS) in resectable PDAC. METHODS: A total of 119 patients who completed AC were analyzed (normal post-AC CA19-9, n = 79; high post-AC CA19-9, n = 40). The upper limit of the normal (ULN) serum level of CA19-9 was 37 U/mL. RESULTS: Median RFS was significantly shorter for patients with high post-AC CA19-9 levels than for those with normal post-AC CA19-9 (10.4 months vs. 29.6 months, respectively; p < 0.001). After adjustment, high post-AC CA19-9 level was an independent predictive factor for short RFS (hazard ratio for RFS, 2.72). Median overall survival was significantly shorter in patients with high post-AC CA19-9 levels than in those with normal postoperative CA19-9 levels (24.7 months vs. 92.1 months, respectively; p < 0.001). The optimal cutoff value of post-AC CA19-9 levels for prediction of early recurrence was >1.5 × UNL (55.5 U/mL), with a 74.2% positive predictive value. CONCLUSIONS: The present results show that high post-AC CA19-9 level is an independent prognostic factor for short RFS in patients with resected PDAC. In addition, it may be useful for predicting early recurrence.