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Ten studies since 1999 have documented high-risk HPVs in breast tumors. The type(s) in breast were identical to those in the cervix of women with cervical cancer. This led to the suggestion of transmission during relationships. In support of this women with HPV-positive breast cancer are significantly younger than those with HPV-negative breast cancer. HPV-associated koilocytes (which are caused by HPV) have been found in breast skin as well as lobules from normal and ductal carcinoma in situ and invasive ductal carcinoma. HPV has been found in the bloodstream of cervical cancer patients as well as male blood donors, where the virus is attached to blood cells [Chen et al., 2009]. Other viruses such as mouse mammary tumor virus (MMTV) and Epstein-Barr virus (EBV) have also been implicated. Although genetic susceptibility is another factor in breast cancer, mutations in BRCA1 and BRCA2 are responsible for only a small proportion of cases. Thus an uncircumcised male partner may also increase a woman’s risk of breast cancer, which is the most frequently diagnosed malignancy in women.