Wednesday, September 30, 2009

High prevalence of pre-cancerous anal lesions in women with HIV

HIV-positive women have a high prevalence of pre-cancerous anal lesions, American investigators report in the January 2nd 2009 edition of AIDS. The researchers found that 12% of HIV-positive women had low-grade pre-cancerous lesions and that high-grade lesions were present in 9% of women. Anal infection with human papilloma virus was an important risk factor for the presence of pre-cancerous anal lesions. There is an increased prevalence of anal cancer amongst people with HIV. A history of anal infection with human papilloma virus has been established as an important risk factor for anal cancer. Pre-cancerous lesions, graded according to their severity (low-grade anal intraepithelial neoplasia, and high-grade anal intraepithelial neoplasia), develop before anal cancer. Only a small percentage of high-grade lesions progress and become anal cancer, and pre-cancerous and cancerous anal lesions can be successfully treated. The sooner such lesions are detected, the higher the chance of treatment being successful. Most of the studies into anal cancer and pre-cancerous anal lesions in HIV-positive individuals have been conducted in gay men. Investigators from the Women’s Interagency HIV Study (WIHS) wished to establish a better understanding of pre-cancerous anal lesions in HIV-positive women and women with a high risk of HIV. They therefore deigned a study to establish the prevalence and risk factors for pre-cancerous anal lesions in these populations. A total of 655 women, 470 of whom were HIV-positive, were recruited included in the investigators analysis. They were evaluated for pre-cancerous anal lesions every six months. Similar proportions of HIV-positive (47%) and HIV-negative (46%) women reported a history of anal intercourse. However, women with HIV were significantly more likely to have abnormal anal cells (31%) when compared to HIV-negative women (9%) (p < 0.003). Furthermore, the investigators found a significantly higher prevalence of anal, cervical and both anal and cervical human papilloma virus in HIV-positive than HIV-negative women (p < 0.001). Low-grade pre-cancerous lesions were detected in 12% of HIV-positive women, but just 1% of HIV-negative women. The investigators then conducted statistical analyses to establish the risk factors for such lesions in women with HIV. In their adjusted analysis that controlled for possible confounding factors, they found that younger age (odds ratio [OR] = 0.59, 95% CI = 0.36-0.97), a history of receptive anal intercourse (OR = 3.2, 95% CI 1.5-6.8), anal infection with strains of human papilloma virus associated with pre-cancerous and cancerous lesions (OR = 11, 95% CI 1.2-103), anal infection with cancer-associated and non-cancer-associated human papilloma virus (OR = 11, 95% CI 1.3-96), and cervical infection with human papilloma virus (both cancer-associated and non-cancer-associated, OR = 3.5, 95% CI 1.1-11). Next the investigators examined the rate of high-grade pre-cancerous anal lesions in the two groups of women. Once again, they found that this was significantly higher (9%) in women with HIV than in HIV-negative women (1%). After controlling for possible confounding factors, the only significant risk factor for this condition in women with HIV was anal infection with human papilloma strains associated with a high-risk of pre-cancerous and cancerous cell changes (OR = 5, 95% CI 0.88-29) and anal infection with human papilloma virus or either a high- and low-risk (OR = 7.6, 95% CI = 1.5-38). “Our findings show that the prevalence of anal intraepithelial neoplasia among HIV-infected women is high and significantly increased above a comparison group of HIV-uninfected women”, write the investigators.


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