Plasma coenzyme Q10 levels and prostate cancer risk: the multiethnic cohort study.

BACKGROUND Coenzyme Q10 (CoQ10) is considered to be a potential anticancer agent, but epidemiologic evidence regarding CoQ10 and prostate cancer risk is lacking. We examined the association of circulating CoQ10 levels with prostate cancer risk, using prediagnostic blood samples. METHODS Each of the 307 cases was individually matched to approximately 2 controls, for a total of 596 controls, on age, ethnicity, geographic location, date/time of specimen collection, and hours of fasting. Logistic regression was used to compute ORs and 95% CIs. RESULTS There was no overall statistically significant association of plasma CoQ10 levels with prostate cancer risk (P(trend) = 0.50). However, after matched sets in which controls who had possible undiagnosed prostate cancer (prostate specific antigen value >4.0) were excluded, the ORs for quintiles 2 to 5 were all less than 1.0. CONCLUSIONS The results suggest the possibility that moderate levels of circulating CoQ10 may be optimal for the reduction of prostate cancer risk; however, the findings were weak and not statistically significant. Because this is the first epidemiologic study of the association between CoQ10 and prostate cancer, further research on this topic is needed. IMPACT If a nutritional factor such as CoQ10 were determined to reduce prostate cancer risk, it would have considerable public health significance because of the very high incidence of this cancer.