CA 19–9 as a predictor of response and survival in patients with pancreatic cancer treated with gemcitabine and cisplatin based chemotherapy

Abstract

15094 Background: Radiologic evaluation of the efficacy of chemotherapy (CT) regimens in pancreatic cancer is complicated by the retroperitoneal location and the desmoplastic nature of the tumor. The aim of this study was to evaluate the role of baseline CA 19–9 and the decrease in CA 19–9 after one cycle of CT as predictors of response, time to progression (TTP) , and overall survival (OS). Methods: We conducted 3 consecutive phase II trials evaluating gemcitabine and cisplatin based CT between 1997 and 2004. A retrospective chart review of the 111 patients yielded demographic data, best response status, TTP, OS, and CA19–9 levels. Response by CA 19–9 (R-CA19–9) was defined as a decrease of = 50% in CA 19–9 after the completion of the first cycle of chemotherapy. Results: The median age was 59 years with 60% males. Median performance status (PS) was 1. No significant difference was observed across the three trials with respect to age, sex, or PS. Baseline CA19–9 was known for 102 patients, and was dichotomized near the median as: < 1,000; and = 1,000 ng/mL. Lower baseline CA19–9 levels were not associated with higher radiologic response (RR) rate (p = 0.82): 22%, and 19%, respectively. Lower baseline CA19–9 was associated with longer OS, (p = 0.0057), as shown in a recent UK study. Median OS was 9.2, and 6.1 months, respectively. Similar results were observed for TTP, with p = 0.0146, and median TTP of 6.4 and 4.2 months, respectively. The change in CA19–9 from baseline to the end of treatment cycle 1 was available for 68 patients. The patients with R-CA19- 9 had a higher RR rate (29%) than did the other patients (24%), but not significantly so (p = 0.7495). The patients with R-CA19–9 had longer OS (median 8.7 vs 7.1 months) and longer TTP (median 7.1 vs 5.4 months), but not significantly so (p > 0.73 for each endpoint). Conclusions: Lower baseline CA19–9 (but not R-CA19–9 after treatment cycle 1) was positively associated with OS and TTP prognosis in our patient population. A 50% decrease in CA19–9 after the first cycle of chemotherapy was not a useful predictor of response, TTP, or OS. No significant financial relationships to disclose.