MELBOURNE – High-grade squamous intraepithelial lesions are prevalent among HIV-positive gay men and a significant number of these anal lesions resolve spontaneously, according to data from a longitudinal observational cohort study.
The Study of the Prevention of Anal Cancer (SPANC) is a 3-year prospective study of the natural history of anal HPV infection, which has so far enrolled 350 homosexual men over 35 years old. Dr. Andrew Grulich from the Kirby Institute, University of New South Wales, Sydney, presented trial data at the 20th International AIDS Conference that showed a 42% clearance rate for high-grade squamous intraepithelial lesions (HSIL).
Bianca Nogrady/Frontline Medical News
Dr. Andrew Grulic
Anal lesions that result from human papillomavirus infection are difficult to treat, and there is no evidence for the effectiveness of treatment, Dr. Grulich said. Further, anal lesions are far less likely than cervical lesions to progress to cancer. However, questions remain about which men are more likely to have persistent high-grade disease and therefore are at a higher risk of progression to cancer.
Interim data from the SPANC study found a 46% prevalence of HSIL among HIV-positive gay men and a 34% prevalence among HIV-negative gay men. The higher rate among HIV-positive individuals was largely driven by a higher prevalence of more advanced anal intraepithelial neoplasia.
Men with persistent infections due to human papillomavirus (HPV) 16 – the subtype most commonly associated with anal cancer – were much less likely to clear the high-grade lesions (hazard ratio = 0.22, 95% confidence interval, 0.11-0.46), as were men with multiple subtypes of HPV.
"What we’ve been able to show is that high-grade disease is very dynamic, with one in six [gay] men getting it and of those who get it about 40% clearing it each year," Dr. Grulich told the conference.
"Not all high-grade disease requires treatment," he said. "These data suggest that treatment can be targeted at those with persistent high-grade disease because much high-grade disease diagnosed on a single occasion will simply go away."
Treatment practices for HSIL vary with some choosing a ‘watch and wait’ approach and others choosing ablative treatment. Dr. Grulich suggested treatment based on "red flags" that suggest a higher risk of progression to cancer.
"If [the patient] is HPV 16–positive, that’s a definite red flag because 90% of anal cancer is caused by that one subtype," Dr. Grulich said. Also, high-grade disease that doesn’t clear is another red flag.
"I think it’s perfectly reasonable, given the state of the science, if you’re doing high-resolution anoscopy and you diagnose (HSIL), to explain to the patient that it’s highly likely to go away but it may not, and therefore get the patient back in about a year," he said.
The study is funded by the National Health and Medical Research Council of Australia, and the Cancer Council NSW. Some authors declared financial ties to pharmaceutical companies including a manufacturer of HPV vaccines.