The aim of this study was to investigate the association between BMI (kg/m2) and prostate cancer risk. BMI is a modifiable lifestyle factor and may provide a unique opportunity for primary prevention of prostate cancer if a causal association exists. Data from 11 886 men from the Carotene and Retinol Efficacy Trial (CARET, 1985–1996 with active follow-up through 2005) comprising current and former heavy smokers were analyzed. CARET was a multicenter randomized, double-blind placebo-controlled chemoprevention trial testing daily supplementation of 30 mg β-carotene+25 000 IU retinyl palmitate for primary prevention of lung cancer. Prostate cancer was a secondary outcome. Nonaggressive disease was defined as Gleason less than 7 and stage I/II. Aggressive disease was primarily defined as at least Gleason 7 or stage III/IV, and secondarily by excluding Gleason 3+4 from the first definition. BMI was calculated from measured weight and height. Cox proportional hazards regression models were used to estimate hazard ratios (HRs) with 95% confidence intervals (CIs) for cancer incidence between BMI categories. During follow-up, 883 men were diagnosed with prostate cancer. In the analysis of aggressive disease when Gleason 3+4 was excluded, men with a BMI of at least 35 kg/m2 had an increased rate of prostate cancer (HR: 1.80, 95% CI: 1.04–3.11, P trend=0.04) compared with men with BMI 18–24.9 kg/m2. No other differences were seen in risk estimates for overall, nonaggressive or aggressive prostate cancer including all Gleason 7 cases, between BMI categories. Our results show an association between having a BMI of at least 35 kg/m2 and an increased risk of aggressive prostate cancer (not including Gleason 3+4 tumors), but do not support an association between BMI and risk of overall, aggressive disease including all Gleason 7, or nonaggressive prostate cancer within a population of current and former heavy smokers.
aDepartment of Medicine, Clinical Epidemiology Unit, Karolinska Institutet, Eugeniahemmet T2, Stockholm, Sweden
bDivision of Public Health Sciences, Cancer Prevention Program, Fred Hutchinson Cancer Research Center
cSwedish Medical Center, Swedish Cancer Institute, Seattle, Washington, USA
Correspondence to Stephanie E. Bonn, PhD, Eugeniahemmet T2, 171 76 Stockholm, Sweden Tel: +46 851 779 173; fax: +46 851 779 304; e-mail: firstname.lastname@example.org
Received July 5, 2017
Accepted October 30, 2017