Screening for HIV-Associated Anal Cancer
Anal cancer occurs at a rate which is 163-fold greater in young men with HIV. It is caused
by another virus, HPV. The incidence has doubled during the HIV epidemic and is not
decreasing despite effective antiretroviral therapy. It is important to have an anal cancer
screening program to detect precancerous lesions; this has been done for the prevention of
cervical cancer through the use of cervical Pap smears.We will do anal Pap smears, HPV
testing and perform high resolution anoscopy for a magnified and detailed view of the anus.
Biopsies are done and early treatment is initiated. It is anticipated that this approach
will help to prevent anal cancer.
The aim of this study is to determine the accuracy of pathology and human papillomavirus
(HPV) testing in identifying precancerous changes in HIV positive men. The primary question
is to determine how good the anal Pap smears are for detecting precancerous changes in the
anus. Secondary questions involve: (a) determination of the test characteristics of the
anal Pap smear, (b) assessment of agreement in visually detecting pre-cancers by the
anoscopists and, (c) a determination of the viral and patient characteristics that predict
This is a cross-sectional survey of HIV positive men with a history of anal receptive
intercourse who are attending several Toronto HIV clinics. Relevant information is
collected as well as anal specimens for assessment. There is a multidisciplinary team who
have the appropriate expertise in these studies.
OUTCOME MEASURES and STATISTICAL ANALYSIS:
The primary outcome measure is the presence of pre-cancerous changes as determined by high
resolution anoscopy. We need to screen 425 subjects in order to find 100 patients with high
grade pre-cancerous changes.
Secondary outcome analyses include specificity, positive predictive value and negative
predictive value of cytology and HPV DNA testing to detect histologically confirmed
pre-cancerous changes or cancer.
Observational Model: Defined Population, Primary Purpose: Screening, Time Perspective: Cross-Sectional, Time Perspective: Prospective
Irving E Salit, MD
Toronto General Hospital
Canada: Ethics Review Committee