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High prevalence of anal infection with high-risk HPV types among HIV-positive women in France
Michael Carter, 2016-01-15 07:20:00
A large proportion of women living with HIV in a national study have an anal infection with types of human papillomavirus (HPV) associated with a high risk of cancer, French investigators report in the online edition of the Journal of Infectious Diseases.
The cross-sectional study involved 311 women who were followed between 2007 and 2012 and tested for the presence of HPV and lesions in the anus in 2012. Anal infection with a high-risk HPV type was detected in 48% of women, with only 26% having a high-risk cervical infection. HPV16, which is associated with an especially high risk of anogenital cancers, was the most prevalent high-risk type in both the anal canal and cervix. A low CD4 cell count, concurrent high-risk cervical HPV infection and cervical lesions were all associated with anal infection with high-risk HPV types.
“The prevalence of anal HPV infection was high in this contemporary cohort of HIV-infected women receiving cART [combination antiretroviral therapy]”, write the investigators. “This high prevalence of anal infection with high-risk oncogenic genotypes is of concern, as it is thought to be a major risk factor for anal cancer.”
HPV is responsible for most cases of cervical and anal cancer. Women living with HIV have an increased risk of HPV infection. However, relatively little is known about the prevalence of and risk factors for anal infection with HPV types associated with a high risk of cancerous cell changes.
Investigators from a study into the cervical health of HIV-positive women in France (VIHGY) therefore designed a sub-study focusing on the prevalence, type and risk factors for anal HPV infection. Women were recruited at five treatment centres. During pelvic examinations, samples were obtained from the anus and cervix and tested for HPV infection and type. A total of 13 HPV types (including HPV16 and HPV18) were considered to pose a high risk of cancerous cell changes; a further eight types were considered potentially carcinogenic.
The following factors were assessed for a possible association with anal high-risk HPV infection: age, sub-Saharan African origin, smoking status, number of lifetime sexual partners, HIV viral load, current and nadir CD4 count, cervical HPV infection status, history of treatment for cervical lesions and concurrent anal and cervical infection with high-risk HPV types.
Participants had an average age of 45 years and 43% were born in sub-Saharan Africa. Median CD4 count was high at 612 cell/mm3 and 84% had an undetectable viral load. Overall, just under 60% of women had a history of low-grade pre-cancerous cervical lesions and 24% had already been treated for cervical lesions.
Forty-eight percent of women had an anal infection with a high-risk HPV type, with 26% having high-risk cervical HPV infection. Potentially carcinogenic HPV types were also more frequently detected in the anal canal than the cervix (22% and 15% respectively). Multiple HPV types were found in the anal canal of 38% of women and the cervix of 18%. High-risk HPV infection was detected in both sites in 16% of women.
HPV16 was the most frequently detected high-risk type detected in both sites, however, prevalence was higher in the anal canal (13%) than the cervix (5%).
After taking into account potential confounders, the factors associated with high-risk HPV infection in the anal canal were a CD4 cell count below 350 cells/mm3 (OR, 2.9; 95% CI, 1.3-6.5), concurrent cervical lesions (OR, 2.6; 95% CI, 1.0-4.3) and cervical infection with high-risk strains of HPV (OR, 1.8; 95% CI, 1.0-3.2).
The investigators believe that the anal canal may be acting as a “reservoir” for high-risk HPV types.
The investigators conclude that HIV-positive women with a low CD4 count, and those with previous HPV-associated cervical lesions are at increased risk of anal high-risk HPV infection. They call for further research to determine the implications of their findings in terms of anal HPV screening strategies.