Does Metformin (Glucophage) Lower Cancer Risk?
Filed Under (Cancer) by David on 15-12-2009
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Metformin (Glucophage drugs , Bristol-Myers Squibb) may help protect against cancer. Researchers from the University of Dundee in the United Kingdom found a 37% reduced risk with metformin and say that their findings warrant a randomized trial. During 10 years of follow-up, cancer occurred in 297 of 4,085 patients (7.3%) new to using metformin, compared with 474 (11.6%) of 4,085 non-users.
Because this was an observational study, the researchers could not control for all differences between study groups. The metformin population seemed to be a different group clinically from the non-users, with a much lower rate of mortality. Some of these rates might have been explained by lower risk of cardiovascular mortality.
The metformin patients also might have had a lower baseline risk of cancer, because they were younger than the non-users; however, their mean body mass index and glycosylated hemoglobin (HbA1c) values were higher. However, having adjusted for known potential confounders, such as other diabetic drugs, smoking, and age, the researchers say that it is unlikely that unknown or residual confounders could account for the entire 37% reduced risk.
The generic metformin users also had a longer median time before cancer developed (3.6 years vs. 2.5 years), but a dose-response analysis showed that their cancer risk was higher during the first two years of follow-up. The reason might be that patients who are just starting to take metformin have more contact with health care professionals and thus cancer would be more likely to be diagnosed. In later years, high maximum doses of metformin were associated with the greatest reduction in risk of treatment cancer.
Source: Diabetes Care 2009;32:1620-1625