Digoxin therapy is not associated with improved survival in epithelial ovarian cancer: A SEER-Medicare database analysis

Objectives. Both in vitro and clinical trial data suggest that cardiac glycosides demonstrate a synergistic antitumor effect when administered with platinum chemotherapy. Epidemiologic studies have also demonstrated improved cancer survival in colorectal, breast, head and neck and hepatocellular carcinoma patients on digoxin therapy at the time of cancer treatment. We sought to determine whether digoxin improves survival in epithelial ovarian cancer patients treated with platinum. Methods. Surveillance, Epidemiology and End-Results (SEER) tumor registries program data on ovarian cancer patients diagnosed in 2007-2009 were linked to Medicare claims data to capture platinum administration, digoxin use and cardiac comorbidities. We analyzed 762 patients who underwent cancer-directed surgery and received platinum chemotherapy. Patients were considered digoxin users during platinum administration if a prescription was filled within 6 months of cancer diagnosis. Cox proportional hazards regression models were used to determine the impact of digoxin use on overall survival (OS). Results. Among 762 epithelial ovarian cancer patients treated with surgery and platinum chemotherapy, 53 (7%) used digoxin ever and 38 (5%) used digoxin specifically during platinum administration. Adjusting for age, heart disease and Charlson comorbidity score, digoxin use was not associated with OS (HR = 1.29, 95% CI 0.81, 2.06). Conclusions. In this SEER-Medicare database analysis, digoxin use during chemotherapy was not associated with improved OS outcomes in patients with epithelial ovarian cancer treated with surgery and platinum chemotherapy. These conclusions are limited, however, by a small sample size and bias intrinsic to claims-based data and should be further evaluated in a larger cohort. (C) 2015 Elsevier Inc. All rights reserved.