For patients with diabetes in the United States, metformin use is associated with reduced risk of developing colorectal cancer (CRC), according to a study published in Cancer.
Amikar Sehdev, M.D., M.P.H., from the University of Chicago, and colleagues examined the effects of metformin on CRC incidence in a U.S. population.
Patients with diabetes and CRC were identified from MarketScan databases. Each case was matched for age, sex, and geographical region with up to two controls; the mean age of study participants was 57 years for cases and 55 years for controls (P = 1.0).
In each group, about 60 percent of participants were male and 40 percent were female. Prescription tracking within the 12-month period before the index date was used to assess metformin exposure.
The researchers found that any metformin use correlated with a 15 percent reduction in the odds of CRC in the multivariable model (adjusted odds ratio, 0.85; 95 percent confidence interval, 0.76 to 0.95; P = 0.007).
The beneficial effect of metformin use was reduced to 12 percent after adjustment for health care use (adjusted odds ratio, 0.88; 95 percent confidence interval, 0.77 to 1.00; P = 0.05).
There was no significant association with metformin dose, duration, or total exposure in dose-response analyses.
“Metformin use appears to be associated with a reduced risk of developing CRC among diabetic patients in the United States,” the authors write.