Metformin improved survival in patients with cancer, diabetes

Patients with cancer and type 2 diabetes treated with metformin experienced longer OS and cancer-specific survival than patients treated with other glucose-lowering medications, according to results of a meta-analysis.

The reduction in risk for death was significant among metformin users with pancreatic and colorectal cancers.

“Metformin can make a substantial difference in outcome for diabetic cancer patients,” researcher Ming Yin, MD, of the department of internal medicine at the Geisinger Medical Center in Danville, Pa, said in a press release.

Yin and colleagues 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 OS, and nine assessed cancer-specific survival.

Researchers found that metformin was associated with improved OS (HR=0.66; 95% CI, 0.55-0.79) and cancer-specific survival (HR=0.62; 95% CI, 0.46-0.84) compared with non-metformin regimens.

Results of a random-effects model analysis indicated 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 lung cancer (HR=0.77; 95% CI, 0.28-2.15), breast cancer (HR=0.64; 95% CI, 0.37-1.12) and prostate cancer (HR=0.66; 95% CI, 0.36-1.21) also demonstrated reduced risks for death, but the results were not statistically significant.
When researchers stratified results by country, the random-effects analysis indicated metformin was associated with a survival benefit in Asian (HR=0.49; 95% CI, 0.37-0.65) and Western countries (HR=0.73; 95% CI, 0.61-0.87).

“Our meta-analysis demonstrated that metformin could be the drug of choice in patients with cancer and concurrent type 2 diabetes if there are no contraindications because it was associated with increased OS and cancer-specific survival compared with other diabetic medications,” Yin and colleagues concluded. “Future prospective studies with larger sample sizes and alternate study design are required to confirm our findings.”

Disclosure: The researchers report no relevant financial disclosures.