Examining the relationship between metformin dose and cancer survival: A SEER-Medicare analysis

• Published in: PloS one Vol. 17; no. 10; p. e0275681
• Main Authors: Scarton, Lisa, Jo, Ara, Xie, Zhigang, O'Neal, LaToya J, Munoz Pena, Juan M, George, Thomas J, Bian, Jiang
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 19.10.2022; Public Library of Science (PLoS)
• Subjects: Aged; Anticancer properties; Antidiabetics; Breast cancer; Cancer; Cancer therapies; Censuses; Chemotherapy; Cohort Studies; Colorectal cancer; Comorbidity; Complications and side effects; Diabetes; Diabetes mellitus; Diabetes mellitus (non-insulin dependent); Diabetes Mellitus, Type 2 - complications; Dosage and administration; Drug dosages; Drug therapy; Epidemiology; Ethnicity; Glucose; Government programs; Health maintenance organizations; Hispanic people; HMOs; Humans; Hypoglycemic Agents - therapeutic use; Male; Medical diagnosis; Medicare; Medicine and Health Sciences; Metformin; Metformin - therapeutic use; Older people; Pancreatic cancer; Pancreatic Neoplasms - drug therapy; Patient outcomes; Patients; Poverty; Prostate; Prostate cancer; Radiation therapy; Regression analysis; Retrospective Studies; Risk factors; Statistical analysis; Surgery; Survival; Type 2 diabetes; United States - epidemiology; United States
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0275681

Cancer is a major health problem in the U.S and type 2 diabetes mellitus (T2DM) is known to increase the risk for the development of many cancers. Metformin, a first-line therapy for treating T2DM, is increasingly being used for its anticancer effects; however, the literature is limited on the effect of metformin dose on overall survival in patients with stage IV cancer. Overall survival was defined as the time interval from the date of diagnosis to the last known follow-up or death from any cause. Subjects who were alive on December 31, 2016 were censored. In this cohort study we examined the relationship between metformin dose and overall survival in persons with both T2DM and stage IV lung, breast, colorectal, prostate, or pancreas cancers. We used a retrospective study design with Cox proportional hazards regression analysis of the 2007-2016 of the Surveillance Epidemiology and End Results-Medicare (SEER) dataset. Of the 7,725 patients, 2,981(38.5%) had been prescribed metformin. Patients who used metformin had significantly better overall survival in both unadjusted (Unadjusted HR, 0.73; 95% CI, 0.69-0.76; p < 0.001) and adjusted models (adjusted HR, 0.77; 95% CI, 0.73-0.81; p < 0.001). The overall survival between patients who took metformin with average daily dose ≥ 1000mg or < 1000mg were not statistically significant (aHR, 1.00; 95% CI, 0.93-1.08; p = 0.90). Metformin use regardless of dose is associated with increased overall survival in older adults with stage IV cancer.