Siobhan Sutcliffe

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Washington University

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PLCO (Learn more about this study)

2009-0556

Nov 9, 2009

Trichomonosis and prostate cancer risk in the Prostate, Lung, Colorectal & Ovarian Cancer Screening Trial

Although inflammation is believed to be an important factor in prostate cancer (PCa) development, responsible cause(s) of inflammation have not yet been identified. Trichomonas vaginalis infection (trichomonosis), a common sexually transmitted protozoan infection known to involve the prostate, has been postulated to be one such responsible cause. To date, we have investigated trichomonosis in relation to PCa risk in three epidemiologic studies of predominantly white men, two of which observed a positive association between T. vaginalis serostatus and PCa, particularly aggressive or late-stage disease, while the third observed no association between T. vaginalis serostatus and very early-stage disease. Although these findings are promising, additional epidemiologic studies are necessary before conclusions can be made. Therefore, we propose to conduct a fourth confirmatory epidemiologic study of trichomonosis and PCa in the PLCO Cancer Screening Trial. This study will include specific analyses for aggressive PCa because trichomonosis has been most consistently associated with this clinically-important outcome, and black men who have not been adequately investigated in previous studies. The proposed study will build upon findings from a previous nested case-control study of other sexually transmitted infections (STIs) and PCa risk in the PLCO cohort. In that study, a modest positive association was observed between a history of any STIs, but not between any of the STIs individually, and PCa, suggesting a possible association between another unmeasured STI and PCa in this cohort. Given previous positive findings for a history of trichomonosis, this STI is clearly a good candidate. The proposed study will also be a "value-added" investigation because it will use the same study design and participants as the previous PLCO study with enrichment for aggressive and black cases; it will incorporate results from previous STI serologic testing; and it will use serum aliquots (110 uL) prepared for a previous canceled STI analysis.