According to a new, worldwide meta-analysis, patients with type 2 diabetes have a significantly increased risk of developing certain types of blood cancers.

A collaborative study led by researchers at The Miriam Hospital (Providence, RI, USA) analyzed 26 (13 case-control and 13 cohort) published observational studies that had evaluated the association between diabetes mellitus type 2 and the incidence of lymphoma, leukemia, and myeloma. The meta-analysis included more than 17,000 cases of type 2 diabetes and blood cancer worldwide. The researchers concluded that patients with type 2 diabetes have about 20% increased risk of developing leukemia, myeloma, and non-Hodgkin lymphoma, as well as a subtype of non-Hodgkin lymphoma known as peripheral T-cell lymphoma. They did not find any associations with Hodgkin lymphoma. The findings suggest type 2 diabetes could be associated with approximately 5% of all incidents of leukemia, myeloma, and non-Hodgkin lymphoma.

The researchers also found that the risk of lymphoma, leukemia, and myeloma appears to differ depending on the geographic region of the original report. For example, the risk of non-Hodgkin lymphoma was higher in Asia and Europe, while there was an increased leukemia risk in the United States and Asia.

“When you consider that [millions of people have type 2 diabetes and that millions more are still likely to develop it], a 20% increased risk of blood cancer is quite significant,” noted lead author Jorge Castillo, MD, a hematologist-oncologist with The Miriam Hospital. He added, “It’s important to remember that type 2 diabetes can, to some degree, be prevented and controlled through lifestyle modification, such as diet and exercise; so by preventing the onset of type 2 diabetes, we could also prevent blood cancer.” Dr. Castillo and colleagues suggested that, in addition to studying antidiabetic therapy, future research should focus particularly on evaluating roles of behavioral factors such as obesity, physical activity, dietary habits, and smoking, which have been linked to both diabetes and cancer.

The findings, published online May 24, 2012, in the American Society of Hematology journal Blood, add to the growing evidence base linking diabetes and certain types of cancer.

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