Anal intraepithelial neoplasia (AIN) in the antiretroviral therapy era

Anal intraepithelial neoplasia (AIN) as a precursor for invasive SCCA has emerged from the recent literature as one of the most important contributions to the field of anal cancer. HIV positive women are more likely to demonstrate abnormal Papanicolaou smears, as well as persistence of cervical infection with HPV over time _[50]. Thus, invasive cervical cancer was added to the list of AIDS-defining conditions in 1993. Not surprisingly, AIN is common among HIV-positive homosexuals, in this population, more than 50% of individuals with a CD4+ count <500, and 33% of those who had a CD4+ count >500 developed AIN within 4 years of follow-up _[51]. Anal colposcopy is a specialised procedure, which should be performed by a trained coloproctologist, using 5% acetic acid epithelial staining in accordance with the techniques used for cervical colposcopy. The rationale for screening this high-risk population with anal Papanicolaou smears is currently under investigation. It appears, however, that AIN does not always progress to SCCA, and that a significant percentage of these lesions undergo spontaneous regression.

In theory, highly active antiretroviral therapy (HAART), which results in improved immune function, may subsequently reduce the risk of HIV-positive homosexuals developing persistent HPV infection in the anal canal. Alternatively, the incidence of AIN may increase over time, since AIDS patients now live longer in the setting of imperfect immune reconstitution. Indeed, recent data regarding AIN and SCCA in the era of HAART give cause for concern. Despite prolonged response to anti-retroviral therapy, HIV-positive homosexuals have persistent HPV infection, and HAART had no effect on the incidence and progression of AIN _[52].

The current consensus is that HAART will probably not be associated with a reversal of high-grade dysplasia, since these lesions have already acquired irreversible chromosomal alterations. Furthermore, epidemiological data from the San Francisco area indicate that the incidence of anal cancer continues to increase substantially despite the widespread use of HAART in this population.

Correspondence:
Pascal Gervaz, MD
Clinique de Chirurgie Viscerale
Hopital Cantonal Universitaire de Geneve
Rue Micheli-du-Crest 24
CH-1211 Geneve
E-Mail: pascal.gervaz@hcuge.ch

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