Environmental exposure to trace elements and prostate cancer in three New Zealand ethnic groups.

A stratified random sample of 176 men was taken from a larger community prostate study group of 1405 eligible subjects from three ethnic groups in the Wellington region of New Zealand, in order to examine ethnic differences in exposure to cadmium (Cd), selenium (Se) and zinc (Zn) and possible associations of blood levels of Cd, Se and Zn with the prevalence of elevated serum Prostate Specific Antigen (PSA); a marker of prostate cancer. Maori and Pacific Islands men were found likely to have higher Cd exposure than New Zealand Europeans through diet, occupation and smoking. However, there was no significant difference between ethnic groups in mean blood Cd levels. Pacific Islands men had significantly higher levels of blood Se than both New Zealand European men and Maori men. Maori men had significantly higher levels of blood Zn than both New Zealand European men and Pacific Islands men. A positive association was found between blood Cd and total serum PSA. Se and Zn levels were not associated with elevated PSA. Maori and Pacific Islands men have higher prostate cancer mortality rates than New Zealand European men. Ethnic differences in mortality could be contributed to by differences in rates of disease progression, influenced by exposure and/or deficiency to trace elements. However, results did not reflect a consistent ethnic trend and highlight the complexity of the risk/protective mechanisms conferred by exposure factors. Further research is needed to ascertain whether the associations found between Cd and PSA levels are biologically important or are merely factors to be considered when interpreting PSA results clinically.

Ethnic differences in diet and associations with clinical markers of prostate disease in New Zealand men.

OBJECTIVE: To examine ethnic differences in diet and dietary associations with clinical markers of prostate disease in New Zealand men. MATERIALS AND METHODS: A total of 1031 males (616 New Zealand European, 230 Maori and 185 Pacific Islands) aged 40-69 years, with no history of prostate cancer, completed a questionnaire covering diet. A serum prostate specific antigen (PSA) blood analysis was also undertaken. Regression models were developed to examine the ethnic-specific levels of selected dietary components, and their relationship with PSA and urinary symptom scores. RESULTS: The results confirmed previously found ethnic differences in the New Zealand diet. Combined tomato intake was positively-correlated with free PSA and % free PSA (p=0.021, r=0.197 and p=0.011, r=0.096 respectively). Beer intake was negatively-correlated with total PSA (p=0.028, r=-0.071) and free PSA (p=0.004, r=-0.094). CONCLUSION: Ethnic differences found in the consumption of foods (associated with prostate cancer) highlight the possible importance of dietary interactions for ethnic prostate cancer risk. Associations between specific foods and PSA warrant further investigation.