Major dietary factors and prostate cancer risk: a prospective multicenter case-control study.

The association between diet and prostate cancer (PC) risk, although suggestive, still remains largely elusive particularly in the Asian population. This study sought to further evaluate the possible effects of different dietary factors on risk of PC in Iran. Using data from a prospective hospital-based multicenter case-control study, dietary intakes of red meat, fat, garlic, and tomato/tomato products, as well as thorough demographic and medical characteristics, were determined in 194 cases with the newly diagnosed, clinicopathologically confirmed PC and 317 controls, without any malignant disease, admitted to the same network of hospitals. Odds ratios (ORs) and corresponding 95% confidence intervals (CIs) were obtained after adjustment for major potential confounders, including age, body mass index, smoking, alcohol, education, occupation, family history of PC, and total dietary calories. Comparing the highest with the lowest tertile, a significant trend of increasing risk with more frequent consumption was found for dietary fat (OR: 1.79, 95% CI: 1.71-4.51), whereas inverse association was observed for tomato/tomato products (OR: 0.33, 95% CI: 0.16-0.65). A nonsignificant increase in PC risk was revealed for dietary red meat (OR: 1.69, 95% CI: 0.93-3.06). For garlic consumption, a borderline reduction in risk was observed (OR: 0.58, 95% CI: 0.32-1.01; P = 0.05). In conclusion, our study supports the hypothesis that total fat may increase PC risk and tomatoes/tomato products and garlic may protect patients against PC.