From University of California - San Francisco
HIV-positive women at high risk for pre-cancerous anal lesions, study shows
HIV-positive women are three times more likely than other women to develop lesions that can lead to anal cancer, new research shows. The greater risk is due at least in part to weakened immune defenses against the common sexually transmitted human papillomavirus (HPV).
The research findings by scientists at the University of California, San Francisco are published in the June 6 issue of the Journal of the National Cancer Institute.
"HPV already has been shown to increase risk of developing cervical cancer, but our research shows HPV also increases abnormal development of anal cells that may lead to anal cancer in women," said Elizabeth Holly, PhD, MPH, lead author of the study and UCSF professor of epidemiology and biostatistics.
Senior author on the study is Joel Palefsky, MD, UCSF professor of laboratory medicine and stomatology, who, along with the other authors on this paper, has made similar findings regarding HIV-positive men.
The researchers conclude that HIV-positive women may benefit from anal exams and assessments of anal cells, although further research is needed. Those with abnormal lesions should be carefully followed up, they say.
In the study, higher rates of anal cancer precursor cells were found in HIV-positive women with anal HPV infection, lower CD4 cell counts (a common indicator of a weakened immune system), a history of anal intercourse and abnormal cervical cells. "We found a number of risk factors associated with increased anal cancer risk among HIV-positive women," Holly said. "But the strongest is the presence of HPV."
HPV, thought to be the most common sexually transmitted agent in the world, is the name of a group of viruses associated with genital warts and anogenital cancer. It is estimated that 75% of the sexually active general population between 15 and 49 years old will have a genital HPV infection at some time in their life. According to the CDC, at any one time about 20 million people in the U.S. have genital HPV infections that can be transmitted to others, and every year about 5.5 million people become infected.
The new findings regarding the association between HPV and anal cancer precursor lesions in HIV-positive women are similar to those regarding HPV and these lesions in HIV-positive men by the same authors, and also similar to the association between HPV and cervical cancer in both HIV-positive and HIV-negative women.
Earlier research by NCI investigators and others have shown that HPV is found in about 99 percent of cervical cancers and 90 percent of anal cancers.
Holly and her colleagues think that women who are exposed to HPV are more likely to get anal cancer as well as cervical cancer because they are prone to anal and cervical cancer precursor lesions, whereas those who don't have HPV are less likely to get these precursor lesions.
The researchers evaluated HPV-related abnormalities in 251 HIV-positive women and 68 HIV-negative women. They completed physical exams and obtained questionnaire data on medical history and relevant sexual practices.
The study was funded by the National Cancer Institute, part of the National Institutes of Health.
Collaborators on the study and co-authors on the JNCI paper are Mary L. Ralston, MS, PhD, senior statistician, epidemiology and biostatistics; Teresa M. Darragh, MD, associate clinical professor, pathology; Ruth M. Greenblatt, MD, professor of medicine; and Naomi Jay, MS, RN, nurse practitioner in stomatology, all at UCSF.