Diabetes Rx Shrinks Cancer Deaths

Prostate cancer patients taking metformin lived longer

/ Author:  / Reviewed by: Robert Carlson, M.D Beth Bolt, RPh

(RxWiki News) A common diabetes medication — metformin — is proving itself to be multi-talented. It’s an inexpensive, highly effective medicine that does more than lower blood sugar levels. Metformin is becoming something of a star in the cancer world.

Prostate cancer patients with diabetes who took metformin for more than six months lived longer than patients who didn’t take the medication.

This medication reduced deaths not only from prostate cancer but from all causes.

"Discuss the different medications you’re taking with your pharmacist."

David Margel, MD in Department of Surgical Oncology at Princess Margaret Hospital in Toronto, led this research.

“There is emerging evidence linking metformin use to decreased cancer risk and improved cancer-related outcomes,” the authors wrote.

The scientists suggest that metformin may influence cancer cells by decreasing insulin levels or by somehow affecting cell duplication and cell death.

This study looked at how survival was affected by the length of time men with diabetes and prostate cancer took anti-diabetic medications.

Participants included 3,837 men who were diagnosed with prostate cancer at an average age of 75 years. The men were followed for an average of 4.64 years.

The researchers found that 1,251 men took metformin before being diagnosed with prostate cancer, and 1,619 took the medicine after their cancer diagnosis.

On average, men took metformin for 19 months before learning they had prostate cancer and 8.9 months following diagnosis.

For every six months of metformin use, prostate cancer–specific death (mortality) declined by 24 percent.

Death from any cause (all-cause mortality) declined 24 percent in the first six months of taking metformin. All-cause mortality was 7 percent lower in men who took metformin between 24 and 30 months compared to prostate cancer patients who didn’t take the medication.

There was no mortality benefit seen in other types of diabetes medications.

“Several studies have suggested metformin use decreases prostate cancer incidence and mortality. The question was whether better control of diabetes was the reason; however, this review clearly shows a reduction in prostate cancer mortality," said E. David Crawford, MD, professor of surgery, urology and radiation oncology and head of the Section of Urologic Oncology at the University of Colorado Health Sciences Center (UCHSC) in Denver, who was not involved in this study.

“These results suggest that metformin may further improve survival as an adjunct [after surgery] therapy, even among those already receiving optimal cancer treatments,” the authors wrote.

They added, “We believe an interventional study of the use of metformin to delay progression in prostate cancer is warranted."

Findings from this study were published August 5 in the Journal of Clinical Oncology.

Grants from the Canadian Cancer Society Research Institute, the Heart and Stroke Foundation of Ontario, the Canadian Diabetes Association/CIHR-Institute of Nutrition and a Metabolism and Diabetes Clinician Scientist Award were used to fund this study. No conflicts of interest were reported.

Review Date: 
August 5, 2013
Last Updated:
August 6, 2013