Dietary zinc and prostate cancer risk: a case-control study from Italy.

OBJECTIVES

Zinc concentration is higher in the prostate than in most other tissues. Since information on the role of zinc on prostate carcinogenesis is controversial, we analysed the issue in a case-control study.

METHODS

Between 1991 and 2002, we conducted a multicentre hospital-based case-control study on prostate cancer in Italy. Cases included 1294 men with incident, histologically confirmed prostate cancer. Controls included 1451 patients admitted to the same hospitals as cases for a wide spectrum of acute non-neoplastic, non-hormone-related diseases. Zinc intake was computed from a valid and reproducible food frequency questionnaire, with the use of an Italian food composition database. Odds ratios (OR) of dietary intake of zinc and the corresponding 95% confidence intervals (CI) were estimated by unconditional multiple logistic regression models, after allowance for several covariates, including total energy.

RESULTS

Compared with the lowest quintile, the OR for the highest quintile was 1.56 (95% CI, 1.07-2.26), with a significant trend in risk (p=0.04). The trend in risk was significant for advanced cancers only, the OR being 2.02 (95% CI, 1.14-3.59) for prostate cancers with a high Gleason score.

CONCLUSIONS

In this large study we found a direct association between high zinc intake and prostate cancer risk, particularly for advanced cancers. Our findings allow one to exclude a favourable effect of zinc on prostate carcinogenesis.