According to a new meta-analysis, cancer patients with concurrent type 2 diabetes who took metformin had better survival than patients who used other types of diabetic medication. The study published in the Oncologist reviewed data from 20 studies that included 13,008 patients with cancer and type 2 diabetes. Of them, 6,343 patients received metformin alone or in combination with another glucose-lowering therapy. The other 6,665 patients received other treatments.

Nineteen of the studies assessed overall survival, and nine assessed cancer-specific survival. Compared with other therapies, there was a relative survival benefit for both cancer-specific (hazard ratio [HR], 0.62) and overall (HR, 0.66) survival with metformin. These results were also observed across subgroups and geographic locations, report Ming Yin, MD, from Geisinger Medical Center in Danville, Pennsylvania, and colleagues.

When analyzed by cancer subtype, the reduction in risk for death was significant in patients with type 2 diabetes and pancreatic (HR=0.65; 95% CI, 0.49-0.86) and colorectal (HR=0.65; 95% CI, 0.56-0.77) cancers. Patients with colorectal, breast, prostate and lung cancer also demonstrated reduced risks for death, but the results were not statistically significant.

In a subgroup analysis that looked at Asian and Western countries, metformin was associated with a reduced mortality risk in Asian countries (HR, 0.49 by fixed effect; P=.150 for heterogeneity). In Western countries, the relative survival benefit remained (HR, 0.73 by random effect; P < .001 for heterogeneity).

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