OBJECTIVES

: Lung cancer is the principal cause of cancer mortality worldwide, accounting for approximately 1.3 million deaths each year. There is increasing evidence of metformin anticancer activity and linking metformin use among diabetic patients to decreased lung cancer risk and improved outcomes, compared to non-diabetic patients. Our objective is to investigate the time from incident antidiabetic drug medication to non-small cell lung cancer (NSCLC) diagnosis among metformin users compared to other antidiabetic drug medication (ADM) users with co-morbid NSCLC and type 2 diabetes (T2D).

METHODS

: We conducted a nested case-control study among Medicare beneficiaries utilizing claims data from the Surveillance, Epidemiology, and End Results (SEER) -Medicare linked database (2007-2013). We selected patients aged older than 66 years with T2D prior to diagnosis of NSCLC. We matched metformin to ADM users demographic characteristics using a propensity score. Kaplan Meier survival curves with log rank tests and multivariable Cox proportional hazards models were used to examine time to NSCLC for matched metformin and ADM users.

RESULTS

: Among 4,652 T2D NSCLC patients, we identified 692 incident metformin users and 161 incident other ADM users, prior to matching. After matching we identified 300 metformin and 100 other ADM users. The overall median time to NSCLC diagnosis was longer in the Metformin (685 days) compared to the other ADM group (523 days; log rank p<0.004). After accounting for various covariates, in the multivariate cox proportional hazard model, there were no statistically significant associations between incident metformin and time to NSCLC.

CONCLUSIONS

: These data suggest that among patients with T2D, metformin use was not associated with prolonged time to NSCLC diagnosis. Future studies with dosing differences of cancer therapies can help determine if metformin is an effective treatment for lung cancer patients in a larger sample.