Pancreatic cancer risk influenced by diabetes duration, treatment
MedWire News: The risk for pancreatic cancer in patients with diabetes is altered by use of sulfonylureas and insulin, say Swiss researchers, but not by use of metformin or long-term duration of diabetes.
Indeed, the team identified a trend toward a decreasing risk for the malignancy in patients with increasing duration of diabetes.
After the first 2 years of diabetes diagnosis, which is associated with a significantly increased risk for pancreatic cancer (OR=3.3), the risk for the malignancy fell significantly, giving an OR of 0.72 and 0.56 after 5 to 10 and more than 10 years, respectively.
"Although uncontrolled confounding by dietary habits or physical activity may be of importance, these findings do not support a causative role for diabetes mellitus for development of pancreatic cancer," say Christoph Meier (University Hospital Basel, Switzerland) and co-authors.
The researchers used data from the UK General Practice Research Database to examine the relationship between diabetes, metformin use, use of other antidiabetes drugs, and the risk for pancreatic cancer. In all, information on 2763 patients with pancreatic cancer, aged an average of 69.5 years, were each matched by age, gender, and other factors to six individuals without the disease.
Although metformin has previously been linked to a reduced overall risk for cancer, long-term use, defined as 30 or more prescriptions, did not significantly reduce the risk for pancreatic malignancy in the study population after adjusting for body mass index, smoking and alcohol habits, and duration of diabetes.
However, further analysis suggested that long-term female users had a significant decreased risk for pancreatic cancer (odds ratio [OR]=0.43).
"This result is somewhat unexpected, and could not be explained by confounding by use of estrogens and should be interpreted with caution since it is based on a limited number of exposed cases and controls, and since there is no obvious patho-physiological explanation," comment Meier et al.
Receiving either 30 or more prescriptions of sulfonylureas or 40 or more prescriptions of insulin was associated with a significantly increased risk for pancreatic cancer (OR=1.90 and 2.29, respectively). Of note, further analysis suggested the increased risk with sulfonylureas largely occurred in women, while the risk with insulin use was found in men.
"As with metformin, these results are based on a limited number of exposed cases and controls and require careful interpretation, since no previously reported data are available, suggesting different effects of sulfonylureas or insulin across genders," the team cautions.
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By Lynda Williams