STD Linked to Prostate Cancer
More Deaths in Men With History of Trichomoniasis
Sept. 11, 2009 -- Infection with a common sexually transmitted disease (STD) may make men more vulnerable to the most deadly form of prostate cancer, new research suggests.
Men in the study who had been infected with the STD trichomoniasis were only slightly more likely to develop prostate cancer years later, compared to men with no documented evidence of prior infection.
But they were nearly three times as likely to die of the disease once they had prostate cancer, epidemiologist and study co-author Lorelei A. Mucci, ScD, tells WebMD.
"Our finding suggests that infection may make prostate cancers more aggressive and more likely to progress," she says.
STD and Prostate Cancer
Trichomoniasis affects both men and women and as many as 7.4 million new infections occur each year, according to the CDC.
The STD is caused by the parasite Trichomonas vaginalis.
Though easily treated with medication, 50%-75% of men with trichomoniasis never develop symptoms so they never find out they have the STD. And many, but not all, clear the infection in a matter of weeks without treatment. Also, people can be reinfected even after treatment.
At least one previous study has suggested a link between trichomoniasis and more aggressive prostate cancers, but that study was smaller and had shorter follow-up than the one reported by Mucci and colleagues in the Sept. 9 online version of the Journal of the National Cancer Institute.
Using data from an ongoing trial involving more than 22,000 male physicians first recruited in 1982, the researchers compared prostate cancer incidence and outcomes among men with and without evidence of infection with the STD.
In all, 673 men who went on to develop prostate cancer and 673 men without cancer matched to the patients for age, smoking status, and follow-up time were included in the analysis.
A history of trichomoniasis infection was confirmed by testing stored blood samples drawn from the men soon after they entered the study.
The samples revealed a slight, but not statistically significant, increase in prostate cancers among men with evidence of a prior infection.
But men who had evidence of prior infection of the STD when they entered the study were far more likely to develop aggressive prostate cancers and they were more likely to die of their cancer.