WEDNESDAY, June 16 (HealthDay News) -- Having type 2 diabetes is associated with an increased risk of several types of cancer, and the increased risk may be due to shared risk factors, though more research is needed to definitively answer many ongoing questions, according to a consensus report released by the American Diabetes Association and the American Cancer Society and published online June 16 in CA: A Cancer Journal for Clinicians.
Edward Giovannucci, M.D., of the Harvard School of Public Health in Boston, and colleagues reviewed the evidence concerning the association of diabetes and various cancer types, as well as risk factors common to both diseases. The researchers looked for any possible biologic links between diabetes and cancer risk, as well as evidence of an association between specific diabetes treatments and an increased cancer risk.
The report states that diabetes is associated with an increased risk of cancers of the breast, pancreas, liver, bladder, endometrium, and colon/rectum, but a decreased risk of prostate cancer. According to the report, the increased risk of some cancers may be due to shared risk factors, such as obesity and inactivity, or more directly tied to hyperinsulinemia or increased inflammation. The authors write that treatment with metformin is associated with a decreased cancer risk, while insulin therapy is associated with an increased risk.
"It is unlikely that the effect of diabetes therapies on cancer risk and progression, particularly at specific cancer sites, will be fully addressed with randomized controlled clinical trials, due to both cost and follow-up time limitations," the authors write. "Given these limitations, multiple well-conducted and appropriately designed prospective observational studies are needed."
Amylin Pharmaceuticals Inc., Lilly USA, Merck & Company Inc., Novo Nordisk A/S, and the Sanofi-Aventis Groupe provided unrestricted support for the consensus development conference. Members of the writing group disclosed financial ties to these and other pharmaceutical and/or medical device companies.
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