Significantly less risk for prostate cancer in diabetes patients
MedWire News: Prostate cancer is significantly less prevalent among men with diabetes compared with men without the condition, UK study results show.
“Observational studies suggest that diabetes is associated with a decreased risk of prostate cancer, but few are population based or have investigated associations with cancer stage or duration of diabetes,” say Richard Martin (University of Bristol) and colleagues.
In addition, Martin and team observed a borderline significant trend for a greater inverse association with well versus poorly differentiated cancers.
They report the results of a nested case-control study of 1291 men with histologically confirmed prostate cancer aged 50–69 years, and 6479 age- and general practice-matched controls from the ProtecT (Prostate testing for cancer and Treatment) study based in the UK.
The team found that the prevalence of diabetes was significantly lower in men with prostate cancer than in controls, at 6.9% versus 8.6%. The presence of diabetes reduced the relative risk for prostate cancer by 22%.
There was weak evidence for the inverse association being greater for well versus poorly differentiated cancers, which was still borderline significant after adjustment for family history of prostate cancer.
Adjustment for body mass index weakened the inverse association slightly further, but it was still statistically significant. There was no evidence for a greater reduction in prostate cancer risk with longer time since diabetes diagnosis.
The authors suggest that low insulin levels in men with diabetes “may suppress prostate carcinogenesis directly or by reducing levels or activity of insulin growth factor-I, a putative risk factor for prostate cancer.”
They conclude in the International Journal of Cancer: “These data add to the evidence of the association of diabetes with prostate cancer in the prostate specific antigen era.”
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By Helen Albert