Serum Zinc and Prostate Cancer Risk in the Multiethnic Cohort study

Abstract

ISEE-0248 Background and Objective: Because zinc is highly concentrated in prostatic tissue and is essential to DNA synthesis, immune function, and antioxidant activity, it may be protective against the development and progression of prostate cancer. On the other hand, because it is essential for androgen production, it may increase prostate cancer risk. In this study, we evaluated the association between prediagnostic serum zinc and subsequent prostate cancer risk in a multiethnic population. Methods: This case-control study was nested within the Multiethnic Cohort of African Americans, Native Hawaiians, Japanese Americans, Latinos, and whites in Hawaii and California. The analysis included 392 incident prostate cancer cases and 783 matched controls over a 1.9-year follow-up period. Multivariate conditional logistic regression was used to estimate odds ratios (OR) and 95% confidence intervals (CI). Results: The mean serum zinc concentration did not significantly differ between cases (94.9 μg/dl) and controls (93.9 μg/dl). No association was found between serum zinc level and prostate cancer either overall or by tumor stage/grade. In ethnic-specific analyses, positive associations were found in Japanese Americans (OR for the highest vs. the lowest tertile = 2.54, 95% CI = 1.08–6.00, P for trend = 0.03) and Latinos (OR = 2.72, 95% CI = 1.04–7.08, P for trend = 0.09), whereas no association was observed in African Americans and whites; however, there was no heterogeneity across ethnic groups (P = 0.11). Additional adjustment for soy intake, the only dietary factor associated with risk in this cohort, did not alter the findings. Conclusion: We found no evidence to support a protective effect of zinc against prostate cancer, and a suggestion in the ethnic-specific results of a possible increase in risk. This offers some support to the hypothesis that higher zinc exposure may increase prostate cancer risk by raising testosterone levels.