Relationship of Type II Diabetes and Metformin Use to Ovarian Cancer Progression, Survival, and Chemosensitivity

OBJECTIVE:To estimate whether metformin use by ovarian cancer patients with type II diabetes was associated with improved survival. METHODS:We reviewed the effect of diabetes and diabetes medications on ovarian cancer treatment and outcomes in a single-institution retrospective cohort. Inclusion criteria were International Federation of Gynecology and Obstetrics stage I–IV epithelial ovarian, fallopian, or peritoneal cancer. Exclusion criteria were noninvasive pathology or nonepithelial malignancies. The primary exposures analyzed were history of type II diabetes and diabetes medications. The primary outcomes were progression-free and overall ovarian cancer survival. RESULTS:Of the 341 ovarian cancer patients included in the study, 297 did not have diabetes, 28 were type II diabetic patients who did not use metformin, and 16 were type II diabetic patients who used metformin. The progression-free survival at 5 years was 51% for diabetic patients who used metformin compared with 23% for the nondiabetic patients and 8% for the diabetic patients who did not use metformin (P=.03). The overall survival at 5 years was 63%, 37%, and 23% for the diabetic patients who used metformin, the nondiabetic patients, and the diabetic patients who did not use metformin, respectively (P=.03). The patients with diabetes received the same treatment for ovarian cancer as the patients without diabetes. The association of metformin use and increased progression-free survival, but not overall survival, remained significant after controlling for standard clinicopathologic parameters. CONCLUSION:In this ovarian cancer cohort, the patients with type II diabetes who used metformin had longer progression-free survival, despite receiving similar treatment for ovarian cancer. LEVEL OF EVIDENCE:II