Type 2 diabetics have reduced risk for prostate cancer
MedWire News: Men who are hospitalized for Type 2 diabetes have a reduced risk for developing prostate cancer than men in the general population, suggest results from a Swedish study.
However, risks for developing other cancers, such as those of the liver and pancreas, were higher in Type 2 diabetic than nondiabetic patients.
“The lower risk for prostate cancer was largest for patients with multiple hospitalizations,” report Kari Hemminiki (German Cancer Research Center, Heidelberg) and colleagues.
The team hypothesized that the chronic metabolic and hormonal disturbances that are characteristics of Type 2 diabetes may predispose to cancer. The researchers compared cancer types and incidence rates among Swedish men and women hospitalized for Type 2 diabetes during 1964–2007, with those among the general population in Sweden during the same period.
Of the 125,126 people hospitalized for Type 2 diabetes during the study period there were 1458 cases of prostate cancer. Hemminiki et al calculated standard incidence ratios (SIRs) for the observed number of cases versus the expected number for men with familial Type 2 diabetes, men whose follow-up began immediately after their last hospitalization, and those whose follow-up began 1 and 5 years after their last hospitalization.
After adjusting results for obesity, the researchers found an elevated risk for 24 cancers among Type 2 diabetes patients compared with the general population, with the highest risk seen for pancreatic (SIR=6.08) and liver cancer (SIR=4.25).
By contrast, Type 2 diabetes patients had a lower risk for prostate cancer than men in the general population, with an SIR of 0.84 for those whose follow-up began 1 year after their last Type 2 diabetes hospitalization.
Prostate cancer risk decreased even further in patients whose follow-up began 5 years after their last Type 2 diabetes hospitalization, with a SIR of 0.77, and was lower still among men who had familial Type 2 diabetes, at a SIR of 0.54.
Notably, remark the researchers, prostate cancer risk dropped to an SIR of 0.42 in patients who were hospitalized three to five times as a result of their Type 2 diabetes, and 0.10 in those with more than five hospitalizations.
“The lower risk for prostate cancer has been observed in other studies, which is consistent with a lower level of serum prostate-specific antigen in diabetics,” writes the team in The Oncologist.
Hemminiki said: “Possibly, a lower level of male sex hormones in diabetics may be among the factors that are responsible for this.”
The team concludes: “Unraveling of the underlying mechanisms may give important clues about the shared pathways of Type 2 diabetes and prostate cancer.”
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By Sarah Guy