HAART has little effect on anal cancer precursor lesions or on HPV

Highly Active Antiretroviral therapy (HAART) seems to have little or no effect on anal squamous intraepithelial lesions (ASIL) – the likely precursor to anal cancer – according to research conducted at the University of California, San Francisco. The same research also suggests HAART has little or no effect on human papillomavirus (HPV).

Until now the effect of HAART on the natural history of ASIL and HPV was unknown.

ASIL severity and level of anal HPV DNA were evaluated among 98 HIV-positive men who have sex with men (MSM) for at least six months before initiation of HAART. The results were compared with those from a six month period after the initiation of HAART. Anal swabs for cytology and HPV studies were obtained, followed by high-resolution anoscopy and biopsy.

Among men whose most severe pre-HAART diagnosis was atypical squamous cells of undetermined significance or low grade ASIL, 18% progressed and 21% regressed six months after starting HAART. Of the study subjects who began with a normal diagnosis, 17% developed ASIL. Only 4% of study subjects (one person) with high grade ASIL regressed to normal.

Dr Joel Palefsky and colleagues report: “There was no reduction in the proportion of study subjects who tested positive for HPV DNA or HPV DNA levels after HAART initiation. The ASIL and HPVA data were similar to those of the pre-HAART comparison period. These results indicate that HAART has little effect on either ASIL of HPV in the first six months after HAART initiation.”

Regarding why treatment was having little or no effect on ASIL development and disease progression when HAART had effectively restored these men’s CD4 counts. Dr Palefsky commented: “My guess is that it’s because HAART is not leading to reconstitution of immune response to HPV specifically.” However, he added: “Another possibility, particularly for people with more advanced ASIL when they begin HAART, is that once one develops high grade disease, the immune response plays less of a role in its natural history. So even if HPV-specific immunity were to improve on HAART, it might have no effect at that stage.”