There are a few cancers where we know that infection plays a part – such as cervical cancer, which is caused by HPV infection, or some cases of cancer caused by the Epstein Barr Virus. Now we may be able to add some cases of prostate cancer to that list, if early results from the US are anything to go by.
Trichomonas infects around 174 million people every year around the world, and can infect the prostate gland. It's thought that infection might cause inflammation, which in turn could trigger cancer. A previous study had found a link between prostate cancer risk and Trichomonas infection, but it was only small. This is a larger study of 673 men with prostate cancer. The researchers looked at blood samples, and compared their infection status with 673 men who didn't have cancer. The samples were taken back in 1982, before cancer had developed.
The researchers found that infection with Trichomonas was associated with a more than two-fold increase in the risk of advanced prostate cancer, and a nearly three-fold increase in prostate cancer that would result in death.
Unfortunately up to three quarters of men infected with Trichomonas may not realise they carry it, since they may not have any symptoms. And clearly, not everyone with the infection goes on to develop cancer. It's worth pointing out that much more work needs to be done to confirm this finding, and to find out how Trichomonas infection is exactly linked to prostate cancer. But if it holds true in larger studies, it would be an important finding, as infection is easily treated with antibiotics. Perhaps this will turn out to be a way to prevent many cases of prostate cancer every year.