Type 2 diabetes mellitus (T2DM) has consistently been associated with decreased risk of prostate cancer, however, if this decrease is related to the use of anti-diabetic drugs is unknown. We prospectively studied men in the comparison cohort in the Prostate Cancer data Base Sweden (PCBaSe) 3. 0, with data on T2DM, use of metformin, sulphonylurea, and insulin retrieved from national health care registers and demographic databases. Cox proportional hazards regression models were used to compute hazard ratios (HR) and 95% confidence intervals (CI) of prostate cancer, adjusted for confounders. The study consisted of 612,846 men, mean age 72 years (standard deviation; SD =9 years), out of whom 25,882 men were diagnosed with prostate cancer during follow up, mean time of five years (SD =3 years). Men with more than one yeaŕs duration of T2DM had a decreased risk of prostate cancer compared to men without T2DM (HR=0.85, 95% CI=0.82-0.88) but among men with T2DM, those on metformin had no decrease (HR=0.96, 95% CI=0.77-1.19), whereas men on insulin (89%) or sulphonylurea (11%) had a decreased risk (HR=0.73, 95% CI=0.55-0.98), compared to men with T2DM not on anti-diabetic drugs. Men with less than one year's duration of T2DM had no decrease in prostate cancer risk (HR=1.11, 95% CI=0.95-1.31). Our results gave no support to the hypothesis that metformin protects against prostate cancer as recently proposed. However, our data gave some support to an inverse association between T2DM severity and prostate cancer risk. This article is protected by copyright. All rights reserved.
International journal of cancer. 2016 Oct 22 [Epub ahead of print]
Christel Häggström, Mieke Van Hemelrijck, Björn Zethelius, David Robinson, Birgitta Grundmark, Lars Holmberg, Soffia Gudbjörnsdottir, Hans Garmo, Pär Stattin
Department of Surgical and Perioperative Sciences, Urology and Andrology, Umeå University, Umeå, Sweden. ., Division of Cancer Studies, King's College London, Faculty of Life Sciences and Medicine, London, UK., Department of Public Health and Caring Sciences/Geriatrics, Uppsala University, Sweden., Department of Surgical and Perioperative Sciences, Urology and Andrology, Umeå University, Umeå, Sweden., Department of Scientific Support, Medical Products Agency, Uppsala, Sweden., Department of Medicine, Sahlgrenska University Hospital, Gothenburg University, Göteborg, Sweden.