Lower risk of dying from any cause over 4.64 year median follow-up period in prostate cancer patients who used metformin
Tuesday, August 13, 2013. In an article published online on August 5, 2013 in the Journal of Clinical Oncology, researchers from Toronto report a lower risk of mortality among prostate cancer patients with diabetes who were being treated with the antidiabetic drug metformin in comparison with those who were not being treated with the drug.
David Margal, MD, PhD at the University of Toronto and his associates evaluated information from 3,837 men with prostate cancer aged 66 years and older identified by the Ontario Diabetes Database. An additional database provided information on antidiabetic medications prescribed to the subjects. There were 1,343 deaths over a 4.64 year median follow-up from the time of diagnosis, among which 291 were caused by prostate cancer.
Metformin was used by 32.6% of the men prior to prostate cancer diagnosis and 42.2% following diagnosis. For each six months of metformin use after diagnosis, there was a 24% reduction in the risk of dying from prostate cancer in comparison with nonusers. There was also a 24% reduction in the risk of death from any cause during the first six months of metformin use, which declined to a 7% reduction with longer use. The authors note that metformin was associated with a benefit regardless of cancer treatments being used; which implies that metformin could help improve survival as an adjunct therapy.
Dr Margal and his coauthors suggest that metformin may reduce the risk of dying from prostate cancer by preventing cancer progression. The drug may influence cancer cells indirectly by reducing insulin levels or directly by affecting the proliferation of cancer cells and apoptosis (programmed cell death). "Because prostate cancer is a slow-growing disease, medication exposures postdiagnosis may have an impact on disease progression and survival and thus may be ideal for secondary prevention strategies," they write.
"Our study is among the first to report that cumulative metformin use after prostate cancer diagnosis is associated with improved all-cause and prostate cancer-specific survival among elderly diabetic men," they announce. "We believe an interventional study of the use of metformin to delay progression in prostate cancer is warranted."