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National Cancer Institute U.S. National Institutes of Health www.cancer.gov
Viral Epidemiology Branch

Research into Prostate and Breast Cancers

Prostate Cancer and Novel Infections

Among African American men, prostate cancer risk was reported to be increased with serologic evidence of prior syphilis, but other associations with sexually transmitted infections or activities have been inconsistent. In FY2006, the Branch completed and submitted for publication a case-control study in which prostate cancer was not associated with KSHV seropositivity in either African or European American men. Contemporaneously, in FY2005, the Branch received approval to test prediagnostic sera from 1100 prostate cancer cases and matched controls in the PLCO cohort with a panel of well validated serologic markers of six sexually transmitted infections. Testing and analysis are expected to be completed in FY2006 and FY2007, respectively.

A previously unknown retrovirus, conditionally named xenotropic murine-related retrovirus (XMRV), was detected in the stromal tissue adjacent to prostate cancers from several men with the homozygous QQ variant of the RNASEL gene, which plays a critical role in innate immunity. IIB has proposed to modify the study of sexually transmitted infections by seeking to detect antibodies against two XMRV antigens in RNASEL homozygous QQ and RR (the common allele) prostate cancer cases and matched controls in the PLCO cohort. This would be completed in FY2007. Subsequent work would depend on the results.

Breast Cancer and Regulatory T Cells

Motivated by the natural history of MMTV infection in mice and the null results of MMTV testing in women with breast cancer, in FY2006 the Branch conducted a pilot study of peripheral blood mononuclear cell phenotypes in 20 early stage women with breast cancer and 20 matched controls. Increased levels of regulatory T cells (CD4 CD25) were found in the cases. This is being pursued with a more specific marker (Fox-P3) and in a larger group of early stage breast cancer cases and controls, which will be analyzed in FY2007. If regulatory T cells in peripheral blood are higher in breast cancer cases than in controls, IIB will seek to use pre-diagnostic specimens from incident breast cancer cases and controls in the PLCO cohort, with expected completion in FY2008. If successful, the project area would be broadened, starting with previously collected case-control specimens, to other malignancies and to measures of innate immunity.