The cause of prostate cancer is not known. One of theories that has been proposed is that it arises from an inflammatory environment caused by infections that can include bacteria, viruses, and sexually transmitted diseases (STDs) such as gonorrhea, syphilis, chlamydia, and trichomonas. This theory gains some support from epidemiological data showing that the likelihood of prostate cancer diagnosis is approximately 50% higher in men who had STDs. However, this observation, which was made in a retrospective review of other studies by a technique known as meta-analysis, must be taken with caution in that it relied upon case-control research design; this design can introduce what is known as recall bias and potentially invalidate the observation. Moreover, contemporary prospective trials have caset doubt on this observation.
It has also been theorized that infections, including STDs, lead to prostatitis. Regardless of a possible direct influence of infections, including STDs, on prostate cancer risk, the question arises as to whether or not prostatitis itself is a risk factor for prostate cancer. The question takes on some meaning because many of the patients participating in the prostatitis surgery clinical trial are found to also have prostate cancer upon pathological inspection of their prostates. A recent publication relating to research conducted with the California Men's Health Study suggests a real association of chronic prostatitis with prostate cancer.
In brief, the study relies upon a multi-racial, multi-ethnic patient sample followed prospectively beginning in 2002. Data relating to demographic characteristics, health status, residential history in the United States, and lifestyle behaviors is collected. Prostatitis was slightly more common in white men than in Latino and African-American men, although Latinos had the longest duration of prostatitis symptoms. There was a 26.3% incidence of STDs, with gonorrhea accounting for 17.1%. 1,658 out of the 68,675 men were diagnosed with prostate cancer during the median followup period of two years; 64.8% of these were classified as "non-aggressive." Its principal findings were that:
One question that the study cannot answer related to the possible causal relationship of prostatitis and prostate cancer. Given that STDs were not associated with prostate cancer risk, one can find no theoretical basis for a model in which inflammation causes both. Likewise, the coincidence of prostatitis and prostate cancer does not prove that one caused the other. It may simply be that men with prostatitis symptoms are much more likely to visit urologists, who are in the business of diagnosing prostate cancer. And so it may simply be that prostatitis is a driver of diagnosis of prostate cancer but not a modifiable risk factor for prostate cancer.
- Men who reported a history of prostatitis had a 30% higher chance of prostate cancer diagnosis
- Those who had prostatitis longest had a further increase in the risk of prostate cancer
- There was no increased risk of prostate cancer with a history of STDs
- The association of prostatitis and prostate cancer was highest among Latinos and Whites