The predictive role of CA 19–9 kinetics for time-to-progression (TTP) and overall survival (OS) in patients receiving palliative first-line chemotherapy for advanced pancreatic cancer

Abstract

e15637 Background: Previous studies showed contradictory results for a predictive role of CA 19–9 kinetics during chemotherapy in patients (pts) with pancreatic cancer (PC). Methods: We performed a retrospective, multicenter study in order to evaluate the role of CA 19–9 as a biomarker for TTP and OS in PC. Main inclusion criteria: histological confirmed diagnosis of PC, treatment with first-line chemotherapy for advanced disease, pre-treatment CA 19–9 level of > 5.2 U/ml. As CA 19–9 measurements were conducted in different laboratories using different commercial assays, we defined a subgroup of pts where CA 19–9 was assessed exclusively by the Elecsys assay (Roche Diagnostics). For the analysis of CA 19–9 kinetics, at least one follow-up measurement between day 20 and 64 during first-line chemotherapy had to be available. Pts were divided into two subgroups of CA 19–9 responders and non-responders by cut-offs of a 25% and 50% decline, respectively. OS and TTP were estimated with the Kaplan-Meier-Method, differences between the subgroups were analyzed by using the log-rank test. Results: One hundred and eighty-six pts were included, 83 of them were tested with the Elecsys method. Median age was 63 years, 90 % of the pts were treated within prospective clinical trials. Median pre-treatment CA 19–9 was 1076 U/ml (range 5.7–100,000 U/ml), the median bilirubin was 0.6 mg/dl. Median OS and TTP were 9.8 months (mo) and 5.4 mo, respectively. In univariate analysis, pts with a CA 19–9 decline of at least 25% during chemotherapy lived significantly longer (11.9 mo vs. 8.2 mo, p=0.003) and had a significantly prolonged TTP (5.8 mo vs. 4.4 mo, p=0.018) than those with a lower decline or even CA 19–9 increase. Data for the Elecsys-measurements were comparable (OS: 13.4 mo vs. 8.6 mo, p=0.004; TTP: 7.0 mo vs. 2.6 mo, p=0.003). None of the analyses demanding a CA 19–9 drop of at least 50% reached the level of statistical significance. Conclusion: An early CA 19–9 decline of 25% during first-line chemotherapy may predict OS and TTP in pts with advanced PC. Innovative statistical methods are required to improve our understanding of the utility of CA 19–9 as a predictive biomarker in PC. [Table: see text]