The Impact of Diabetes Mellitus and Metformin Treatment on Survival of Patients with Advanced Pancreatic Cancer Undergoing Chemotherapy

Purpose A causal relationship between diabetes mellitus (DM) and pancreatic cancer is well established. However, in patients with advanced pancreatic cancer (APC) who receive palliative chemotherapy, the impact of DM on the prognosis of APC is unclear. Materials and Methods We retrospectively enrolled APC patients who received palliative chemotherapy between 2003 and 2010. The patients were stratified according to the status of DM, in accordance with 2010 DM criteria (American Heart Association/American Diabetes Association). DM at least 2 years' duration prior to diagnosis of APC was defined as remote-onset DM (vs. recent-onset). Results Of the 349 APC patients, 183 (52.4%) had DM. Among the patients with DM, 160 patients had DM at the time of diagnosis of APC (remote-onset, 87; recent-onset, 73) and the remaining 23 patients developed DM during treatment of APC. Ultimately, 73.2% of patients (134/183) with DM received antidiabetic medication, including metformin (56 patients, 41.8%), sulfonylurea (62, 45.5%), and insulin (43, 32.1%). In multivariate analysis, cancer extent (hazard ratio [HR], 1.792; 95% confidence interval [CI], 1.313 to 2.445; p < 0.001) showed association with decreased overall survival (OS), whereas a diagnosis of DM (HR, 0.788; 95% CI, 0.615 to 1.009; p=0.059) conferred positive tendency on the OS. Metformin treatment itself conferred better OS in comparison within DM patients (HR 0.693; 95% CI, 0.492 to 0.977; p=0.036) and even in all APC patients (adjusted HR, 0.697; 95% CI, 0.491 to 1.990; p=0.044). Conclusion For APC patients receiving palliative chemotherapy, metform in treatment is associated with longer OS. Patients with DM tend to survive longer than those without DM.