Anal cancer and HPV screening in HIV positive people
Anal cancer is a serious issue in people with HIV even after long term ART.
One third of MSM worldwide are infected with HPV type 16, which is responsible for 80 to 90% of anal cancers. Charles Lacey from University of York discussed approaches to prevent HPV associated anal cancer in HIV positive people.
Current prevention strategies against anal cancer in HIV positive people include vaccination against HPV in adolescent boys, vaccination in MSM aged 16 to 45, starting ART at higher CD4 counts, maintaining prolonged HIV suppression with ART and stopping smoking. The Joint Committee on Vaccines and Immunisation has recommended that vaccination of MSM aged 16 to45 would be cost effective, but the Department of Health, Public Health England and NHS England have yet to make a decision on its implementation.
Dr Lacey discussed various studies that have assessed risk factors for anal cancer and anal intraepithelial neoplasia (AIN). These studies showed that the risk of cancer decreased significantly for those who maintained an undetectable viral load at least 60% of the time (OR 0.51), and for those with higher CD4 count nadirs (above 350, OR 0.34). In contrast current smoking was significantly associated with higher risk of anal cancer (O.R. 2.59).
Screening programmes for anal cancer include anal cytology which is currently the screening test of choice, digital ano-rectal examination (DARE), which may be cost effective if used to screen HIV positive men older than 50 years every four years, and serial HPV viral load testing which may predict anal disease evolution.
Treatment options for AIN2/3 include ablation (laser, electrocautery, or infrared coagulator), imiquimod, or 5-FU. While these treatments can result in complete responses in percentage of cases, 66% of patients experienced recurrences at 1.5 years.
Finally, Dr Lacey discussed ‘good’, ‘better’ and ‘best’ prevention strategies for anal cancer in HIV positive MSM. The latter of these includes vaccination, initiating ART at HIV diagnosis, discouraging smoking, DARE-screening, and HPV-16 DNA and viral load testing, as well as a new effective treatment regimen that combines ablation with therapeutic vaccination.
Lacey C. Anal cancer prevention strategies including screening for HPV-related diseases in HIV-positive patients. 22nd Annual BHIVA Conference, 19-22 April 2016, Manchester. Invited lecture.
http://www.bhiva.org/documents/Conferences/2016Manchester/Presentations/160421/CharlesLacey.pdf (PDF slides)