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AUA 2017

AUA 2017: Improved Recurrence Free Survival in NMIBC Patients Taking Metformin Demonstrates Dose Dependence

Boston, MA (UroToday.com) There has been published literature showing that Metformin may affect recurrence of non-muscle invasive bladder cancer (NMIBC). Dr. Rushmer presented a study that evaluated the association of Metformin among common prognostic factors for bladder cancer recurrence in a multivariate model and assessed whether Metformin demonstrates a dose dependent effect.

A single institutional database including 503 patients treated with transurethral resection (TUR) for NMIBC were initially analyzed. These patients were followed longitudinally having an additional 682 recurrences and subsequent TURs. Overall, 1185 TURs were performed on these 503 patients. A total of 144/503 cases of NMIBC TURs, in 60 unique patients, met the inclusion criteria and were taking Metformin at the time of TUR.

Results demonstrated that the median age was 70.6 years with a median time to recurrence of 15 months (IQR 6.18-35.6). On univariate analysis, factors associated with statistically significant improved recurrence free survival (RFS) included: metformin use at TUR (p=0.01, HR 0.61, 95% CI 0.42-0.89), metformin dose ≥2000 mg (p=0.03, HR 0.50, 95% CI 0.28-0.90), age, multifocality, tumor size, perioperative Mitomycin-C, bacillus Calmette-Guerin therapy, and intravesical chemotherapy. Multivariate analysis demonstrated improved RFS when comparing diabetic patients on metformin at TUR to diabetic patients not on metformin (p=0.0002, HR 0.51, 95% CI 0.36-0.72) and improved RFS even when comparing diabetic patients on metformin to non-diabetic patients not on metformin (p=0.0001, HR 0.60, 95% CI 0.46-0.77). A separate multivariate analysis, demonstrated improved RFS when comparing patients taking ≥2000 mg of metformin to patients taking <2000 mg at the time of TUR (p=0.0054, HR 0.39, CI 0.20-0.76). The 5-year RFS rate was 42.3% for diabetic patients on metformin, 35.1% for non-diabetics not on metformin, and 9.7% for diabetic patients not treated with metformin (p=0.0001).

This study demonstrates a clear advantage for Metformin use at the time of TUR, being associated with improved 5 year RFS in a multivariate model. Additionally, Metformin dose ≥2000 mg is independently associated with improved RFS.

Presented By: Timothy Rushmer, Madison, WI

Written By: Hanan Goldberg, MD, Urologic Oncology Fellow (SUO), University of Toronto, Princess Margaret Cancer Centre

at the 2017 AUA Annual Meeting - May 12 - 16, 2017 – Boston, Massachusetts, USA