Anal HPV Infection and Abnormal Cytology in HIV-infected Women

BACKROUND FOR THIS STUDY Anal cancer is a growing problem in the US. The incidence of anal cancer has increased among both men (160%) and women (78%) from 1973 to 2000 in the US [1]. In HIV-infected men the incidence of SCCA (squamous cell cancer of the anus) was found to range from 49-92 per 100,000 patient years [2]. This prompted recommendations on screening for anal cancer in this population. HIV-infected women are also at increased risk for developing anal cancer. A study based on data from AIDS and cancer registries found that the risk of anal cancer among women in the general population is about 1.2% and it increases up to 3.9% in the HIV-infected women. In addition, HIV-infected women had eight times the risk of in situ anal cancer compared with the number of expected cases [3].

SCCA appears to have many similarities to cervical cancers. HPV has been detected in 88% of anal cancer specimens with HPV-16 found in 73% of SCCA and HPV-18 in 7% [1]. In addition, SCCA develops in the transformation zone between the squamous epithelium of the anus and the columnar epithelium of the rectum, is frequently associated with dysplasia of the anus and may be preceded by squamous intraepithelial changes which are also associated with HPV.

Cervical cytology, also known as pap smear, can detect cervical cancer and its precursors. Countries who have adopted cervical cancer screening programs have had dramatic decreases in both the morbidity and mortality rates of cervical cancer.

Anal cytology may also be used to screen for HPV associated anal lesions, and among HIV-infected men who have sex with men, an abnormal cytology is frequently associated with a dysplastic squamous cell lesion of the anus. Anal HPV infections (high risk types) have been found in 53 ¿ 95% of HIV-infected men. Abnormal anal cytology has been found in 41-81% of HIV-infected men screened with high-grade cytologic findings in 2-25% of these patients [2].

There have been only a few studies looking at anal cytology in HIV-infected women. The largest study (n=235), by Holly and Palefsky [4], found that HIV positive women had a 26% prevalence of anal cytologic abnormalities (mostly atypical squamous cells of undetermined significance [ASCUS] and low grade squamous intraepithelial lesions [LSIL]). Forty-six of these women with abnormal cytology (60) underwent high resolution anoscopy (HRA) and 14 were found to have biopsy proven HSIL.