New study below [1].
"Trichomonas vaginalis is an anaerobic, flagellated protozoan parasite and the causative agent of trichomoniasis. It is the most common pathogenic protozoan infection of humans in industrialized countries. Infection rates between men and women are similar with women being symptomatic, while infections in men are usually asymptomatic. Transmission usually occurs via direct, skin-to-skin contact with an infected individual, most often through vaginal intercourse. The WHO has estimated that 160 million cases of infection are acquired annually worldwide. The estimates for North America alone are between 5 and 8 million new infections each year, with an estimated rate of asymptomatic cases as high as 50%." [2]
There are 26 PCa hits on PubMed, where papers often open by describing the role of Trichomonas vaginalis (TV or T. vag) as being "controversial.
Unlike other STDs, a man might have no symptoms - providing oportunity for prostate infection.
[3] Studies where Siobhan Sutcliffe was the lead, author or co-author. It's a mixed bag.
[3a] (2006 - U.S. - Health Professionals Follow-up Study)
"Although several previous case-control studies have investigated associations between sexually transmitted infections (STI) and prostate cancer, most have focused on gonorrhea and syphilis, two well-recognized, symptomatic STIs. Another STI of interest for prostate carcinogenesis is trichomonosis, a less well recognized and frequently asymptomatic STI with known prostate involvement."
"Thirteen percent of cases and 9% of controls were seropositive for trichomonosis (adjusted odds ratio, 1.43 ...)"
"Interestingly, this association was strongest among men who rarely used aspirin, and weakest among men who used aspirin regularly over the course of their lives and thus presumably at the time of infection."
[3b] (2009 - U.S. - Prostate Cancer Prevention Trial)
"No association was observed between T. vaginalis serostatus and prostate cancer. 21.5% of cases and 24.8% of controls had low seropositivity, and 15.2% and 15.0% had high seropositivity."
[3c] (2009 - U.S. - Physicians’ Health Study)
"Although not statistically significant, the magnitude of the association between T vaginalis–seropositive status and overall prostate cancer risk (OR = 1.23 ...) was similar to that reported previously {in [3a]}."
"Furthermore, a seropositive status was associated with statistically significantly increased risks of extraprostatic prostate cancer (OR = 2.17 ...) and of cancer that would ultimately progress to bony metastases or prostate cancer–specific death (OR = 2.69 ...)."
[3d] (2013 - U.S. - Health Professionals Follow-up Study again)
"... we investigated effect modification by Toll-like receptor 4 (TLR4) variation on" the "positive association between Trichomonas vaginalis serostatus and risk of prostate cancer"
"Although not statistically significant, TLR4 variation appeared to influence the association between T. vaginalis serostatus and prostate cancer risk consistent with the hypothesis that inflammation plays a role in this association."
[3e] (2016 - U.S.)
"A total of 146 men with advanced (metastatic or fatal) prostate cancer and 181 age-matched controls were selected from two prior population-based, case-control studies."
"The seroprevalence of Tv in controls was 23%. Tv serostatus was not associated with an increased risk of metastatic or fatal prostate cancer (ORs < 1)"
...
In the new study ("Trichomonas vaginalis: a possible foe to prostate cancer."):
"Prostate cancer (PCA) is the most common malignancy in men in USA, and the role of Trichomonas vaginalis (T. vag) in the development of PCA is still controversial."
"Culture supernatant of T. vag inhibits growth of PC-3 prostate cancer cells ..."
"Culture supernatant of T. vag induced apoptosis of PC-3 cells"
"The growth inhibition effect of culture supernatant of T. vag is also demonstrated in another prostate cancer cell line DU145, suggesting that its effect is not specific to one prostate cancer cell line."
"Culture supernatant of T. vag inhibits growth of prostate cancer by inhibition of proliferation and promotion of apoptosis."
{"supernatant" is a liquid - perhaps obtained via centrifugation}
-Patrick
[1] ncbi.nlm.nih.gov/pubmed/276...
[2] en.wikipedia.org/wiki/Trich...
[3a] cebp.aacrjournals.org/conte...
[3b] ncbi.nlm.nih.gov/pmc/articl...
[3c] ncbi.nlm.nih.gov/pmc/articl...
