Hypothetic association between human papillomavirus infection and breast carcinoma.

High-risk human Papillomaviruses (HPVs) has been proved to be the major cause of cervical cancer. It has been considered that HPV may also cause squamous cell carcinomas of the other sites such as anus, vulva and esophagus. Furthermore, a number of studies have detected HPV DNA in breast carcinoma tissues. This raises the question that whether HPV plays a carcinogenic role in breast carcinomas. On the other hand, human Papillomaviruses do not seem to be able infect normal mammary cells in vitro, nor have HPV infections in human breast glands been observed among patients with AIDS. At present, there is no explanation for these "conflicting observations". In this paper, we propose the hypothesis that mammary epithelial cells that partly lose control in proliferation are more susceptible for persistent HPV infection. The potential role of HPV infection in the carcinogenic steps of breast cancer should be further tested. One possible cost-effective way for further investigation is to conduct a case-control study comparing the prevalence of previous HPV exposure to the breast, such as history of cervical HPV infections and HPV infections in nipples between cases and controls.