Sexually Transmitted Disease Linked to Aggressive Prostate Cancer

Men who are seropositive for Trichomonas vaginalis, the causative agent of trichomoniasis, a sexually transmitted disease (STD), are at risk for more advanced prostate cancer than men who are seronegative.

Scientists first reported an association between plasma antibodies to Trichomonas and risk of prostate cancer in the year 2006. This analysis found that 13% of prostate cancer cases were seropositive for Trichomonas compared with 9% of controls. They reported a 43% increased incidence of prostate cancer in men who were seropositive compared with controls. This effect was stronger in men who did not take regular aspirin

The current analysis included 673 patients with prostate cancer and 673 controls without prostate cancer. Prevalence of seropositivity for Trichomonas was 21% in the control group and 25% in the prostate cancer group. The overall risk (OR) of prostate cancer was 1.23 in the seropositive group, but this was not a statistically significant difference. However, the scientists found that men who were seropositive were twice as likely to have advanced-stage prostate cancer as controls and were at an even higher risk (OR=2.69) for death or metastatic disease from prostate cancer. The authors suggest that these data support the association between Trichomonas infection and prostate cancer.

These data are do not prove conclusively that T. vaginalis infection plays a major role in the etiology of prostate cancer in the United States. Trichomonas infects millions of men worldwide and is common in Asia, where prostate cancer is relatively rare; this makes Trichomonas an unlikely candidate as a major cause of prostate cancer. However, the data appears to provide support for the belief that inflammation is related to the development of prostate cancer.

Sexually transmitted diseases have not been linked directly to the development of prostate cancer, although there has been much speculation about the role of inflammation in prostate cancer etiology. Trichomonas is a very common sexually transmitted parasitic disease that affects 170 million men and women in the world. Trichomonas has not been included in previous studies of sexually transmitted diseases related to prostate cancer. The latter study was published in the early online publication of the Journal of the [U.K.] National Cancer Institute on September 8, 2009

Scientists affiliated with the Physicians' Health Study carried out the investigations. Their original study was begun in 1982 to test the benefits and risks of aspirin and beta carotene in the primary prevention of cardiovascular disease and cancer. In the intervening years, more than 300 published scientific reports have appeared and the investigations are continuing.

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Physicians' Health Study