Journal of the National Cancer Institute Advance Access published online on September 9, 2009
JNCI Journal of the National Cancer Institute, doi:10.1093/jnci/djp306
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© The Author 2009. Published by Oxford University Press.
ARTICLE |
Prospective Study of Trichomonas vaginalis Infection and Prostate Cancer Incidence and Mortality: Physicians' Health Study
Affiliations of authors: Department of Epidemiology (JRS, GJ, ELG, KF, TK, MJS, LAM) and Department of Nutrition (ELG, MJS), Harvard School of Public Health, Boston, MA; Channing Laboratory (JRS, ELG, JM, MJS, LAM) and Division of Preventive Medicine (TK), Department of Medicine, Brigham and Women’s Hospital and Harvard Medical School, Boston, MA; School of Molecular Biosciences, Washington State University, Pullman, WA (JFA, VM, ASK); Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD (EAP); Alvin J. Siteman Cancer Center and Department of Surgery, Washington University School of Medicine, St. Louis, MO (SS); Department of Medical Epidemiology and Biostatistics, Karolinska Institutet, Stockholm, Sweden (KF); Institut National de la Santé et de la Recherche Médicale, Unit 708 Neuroepidemiology and Pierre et Marie Curie University, Paris, France (TK)
Correspondence to: Jennifer R. Stark, ScD, Department of Epidemiology, Harvard School of Public Health, 677 Huntington Ave, Boston, MA 02115 (e-mail: stark{at}hsph.harvard.edu).
Background: A recent nested case–control study found that the presence of antibodies against Trichomonas vaginalis, a common nonviral sexually transmitted infection, was positively associated with subsequent incidence of prostate cancer. We confirmed these findings in an independent population and related serostatus for antibodies against T vaginalis to prostate cancer incidence and mortality.
Methods: We conducted a case–control study nested within the Physicians’ Health Study that included 673 case subjects with prostate cancer and 673 individually matched control subjects who had available plasma samples. Plasma from blood samples collected at baseline was assayed for antibodies against T vaginalis with an enzyme-linked immunosorbent assay. We used conditional logistic regression to estimate the odds ratios (ORs) of incident prostate cancer, extraprostatic prostate cancer, and cancer that would ultimately progress to bony metastases or prostate cancer–specific death.
Results: Although not statistically significant, the magnitude of the association between T vaginalis–seropositive status and overall prostate cancer risk (OR = 1.23, 95% confidence interval [CI] = 0.94 to 1.61) was similar to that reported previously. Furthermore, a seropositive status was associated with statistically significantly increased risks of extraprostatic prostate cancer (OR = 2.17, 95% CI = 1.08 to 4.37) and of cancer that would ultimately progress to bony metastases or prostate cancer–specific death (OR = 2.69, 95% CI = 1.37 to 5.28).
Conclusions: This large prospective case–control study obtained further support for an association between a seropositive status for antibodies against T vaginalis and the risk of prostate cancer, with statistically significant associations identified for the risk of extraprostatic prostate cancer and for clinically relevant, potentially lethal prostate cancer.
| CONTEXT AND CAVEATS Prior knowledge The presence of antibodies against Trichomonas vaginalis, a common nonviral sexually transmitted infection, has been positively associated with subsequent incidence of prostate cancer. Study design Nested case–control study that included case subjects with prostate cancer and individually matched control subjects who had available plasma samples that were collected at baseline. Plasma was assayed for antibodies against T vaginalis. The relationship of incident prostate cancer, extraprostatic prostate cancer, and cancer known to progress to bony metastases or prostate cancer–specific death was investigated. Contribution The size of the association between T vaginalis–seropositive status and overall prostate cancer risk, although not statistically significant, was similar to that reported previously. A seropositive status was associated with statistically significantly increased risks of extraprostatic prostate cancer, cancer that is known to progress to bony metastases, or prostate cancer–specific death. Implications Further investigation is warranted to determine whether local prostatic inflammation could lead to downstream events that influence prostate cancer risk and to confirm the association between T vaginalis serostatus and aggressive prostate cancer. Limitations The time between T vaginalis infection and blood collection was not known. Men with T vaginalis infection might visit their physicians more frequently than those without such infection and so increase the possibility of prostate cancer diagnosis. Because other sexually transmitted infections occur concurrently with T vaginalis infections, the possibility that T vaginalis is acting as a marker for another pathogen cannot be ruled out. From the Editors
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Manuscript received February 17, 2009; revised July 21, 2009; accepted August 4, 2009.
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J Natl Cancer Inst 2009 101: 1365.