Body size and dietary risk factors for aggressive prostate cancer: a case-control study.

PURPOSE: Diet and body size may affect the risk of aggressive prostate cancer (APC), but current evidence is inconclusive. METHODS: A case-control study was conducted in men under 75 years of age recruited from urology practices in Victoria, Australia; 1,254 with APC and 818 controls for whom the presence of prostate cancer had been excluded by biopsy. Dietary intakes were assessed using a validated food frequency questionnaire. Multivariable unconditional logistic regression estimated odds ratios and confidence intervals for hypothesized risk factors, adjusting for age, family history of prostate cancer, country of birth, socioeconomic status, smoking, and other dietary factors. RESULTS: Positive associations with APC (odds ratio, 95% confidence intervals, highest vs. lowest category or quintile) were observed for body mass index (1.34, 1.02-1.78, Ptrend = 0.04), and trouser size (1.54, 1.17-2.04, Ptrend = 0.001). Intakes of milk and all dairy products were inversely associated with APC risk (0.71, 9.53-0.96, Ptrend = 0.05, and 0.64, 0.48-0.87, Ptrend = 0.012, respectively), but there was little evidence of an association with other dietary variables (Ptrend > 0.05). CONCLUSIONS: We confirmed previous evidence for a positive association between body size and risk of APC, and suggest that consumption of dairy products, and milk more specifically, is inversely associated with risk.