Human papillomavirus (HPV) is the term given to a group of viruses that are sexually transmitted. There are many subtypes of HPV, including HPV-16, HPV-18 and so on. Infection with HPV can cause genital warts in both men and women. HPV can also cause abnormal growths on the cervix and vulva. Sometimes these growths are harmless or benign, but in other cases they can develop into pre-cancerous lesions and sometimes tumours.

One factor affecting the ability of these lesions to transform into a more dangerous state is the certain subtype of HPV a person is infected with. Subtypes such as HPV-16, HPV-18 and HPV-31 are linked to the development of pre-cancerous growths as well as cancer of the cervix, anus and penis. Another target that HPV attacks in women is the vulva. Researchers in the United States have conducted a study in two groups -- 1,562 HIV positive women and 469 HIV negative women -- to find out about risk factors for developing the following:

• genital warts
• abnormal growths and tumours on the vulva

The research team monitored HIV women for up to eight years. Key findings were as follows:

• Both HIV positive and HIV negative women who had abnormal Pap smears were at high risk for developing genital warts.
• HIV positive women were at least three times more likely to develop genital warts than HIV negative women.
• Having higher CD4+ counts as a result of highly active antiretroviral therapy (HAART) reduced the risk of developing genital warts in HIV positive women.

Further details about the impact of HAART on genital warts and vulvar cancer appear later in this story.

Study Details

All participants underwent detailed medical interviews twice a year, had vulvar examinations and, if lesions were present, then gynecologists had a closer look at the lesions with vulvar colposcopy. Biopsies were taken from lesions but not genital warts. Blood samples were collected and analysed. On average, women in this study were between 30 and 40 years old, 50% were black, 80% had children, and at least half the women were smokers. This study was part of the Women?s Interagency HIV Study (WIHS).

Results -- Genital warts

• Both HIV positive and HIV negative women who had abnormal Pap smears were at high risk for developing genital warts.
• All women who smoked were at increased risk of developing warts.
• Overall, HIV positive women were at least three times more likely than HIV negative women to develop genital warts.
• Among HIV positive women, the higher their CD4+ count, the lower their risk of developing warts.
• In one analysis, HAART use itself was not associated with a decreased risk of warts in this study. However, those women whose CD4+ cell counts rose as a result of HAART had a reduced risk of warts.

Results -- Focus on the Vulva

As with genital warts, HIV positive women were three times more likely than HIV negative women to have abnormal cells on their vulva. The good news was that generally these cells in both groups were only mildly abnormal. Other findings included the following:

• Abnormal cells on the vulva were more likely to occur in women who had abnormal Pap smears.
• HIV positive women who used HAART were at lower risk of having abnormal cells on their vulva.
• Similarly, women who had higher CD4+ cell counts were less likely to have abnormal cells on their vulva than women with lower CD4+ cell counts.

Cancer

There were no cases of vulvar cancer among HIV negative women in this study. Despite twice-yearly tests and examinations, three cases of vulvar cancer occurred among 1,562 HIV positive women over eight years. The good news is that these cancers were detected at an early stage in their development, perhaps because of frequent medical check-ups.

Screening Issues for HIV-Positive Women

In this study HIV positive women who had abnormal Pap smear results were highly likely to also have abnormal growths on their vulva. Yet, colposcopic examination of the vulva was not a routine part of this study and most abnormal growths on the vulva were found by simply having a gynecologist closely examine them with the naked eye. Therefore, based on the results of their study, the research team does not encourage the regular use of vulvar colposcopy for HIV positive women. They do emphasize that "careful genital inspection is mandatory" for all women who have abnormal Pap smears. Also, women with visible growths on their vulva should have biopsies performed to assess the nature of these growths. This study underscores the need for HIV positive women to receive regular gynecologic exams, including Pap smears.

Reference

1. Massad LS, Silverberg MJ, Springer G, et al. Effect of antiretroviral therapy on the incidence of genital warts and vulvar neoplasia among women with the human immunodeficiency virus. American Journal of Obstetrics and Gynecology 2004;190(5):1241-1248.