Cancer Causes Control. 2009 Aug 4. [Epub ahead of print]
Metformin use and prostate cancer in Caucasian men: results from a population-based case-control study.
Wright JL, Stanford JL.
Department of Urology, University of Washington School of Medicine, Seattle, WA, USA,
Metformin is a commonly used medication for type II diabetes mellitus.
Epidemiologic studies have suggested a decreased relative risk of
cancer with metformin use, and preclinical studies of prostate cancer
(PCa) have shown antitumor activity with metformin. In this study, we
explore the relationship between metformin use and PCa risk in a
population-based case-control study.
METHODS: Cases were men aged 35-74
years diagnosed with PCa between 2002 and 2005 in King County,
Washington. Controls were frequency matched by age and identified by
random digit dialing. Use of metformin was determined from in-person
questionnaires regarding medical and prescription history. The
relationship of metformin use with PCa risk was evaluated using
RESULTS: A total of 1,001 cases of PCa and 942
controls were available for analysis. In Caucasian men, metformin use
was more common in controls than in cases (4.7 vs. 2.8%, p = 0.04),
resulting in a 44% risk reduction for PCa (adjusted OR = 0.56; 95% CI
0.32-1.00). No association was seen in African-American men.
CONCLUSION: Metformin use was associated with a borderline significant
decrease in the relative risk of PCa in Caucasians. Further study into
this relationship is needed to confirm the association and determine
the underlying pathways involved.