Up to 62% of people living with HIV who have high-grade pre-cancerous cell changes may experience
an improvement in their condition over two years without any treatment,
according to the results of a modelling study presented to the recent Conference on Retroviruses and Opportunistic Infections (CROI) in Boston earlier this month.
Investigators from University of California, San Diego based the
model on observed outcomes in over 2800 people with high-grade pre-cancerous
anal cell changes who received care between 2001 and 2012. Calculated rates of
progression to anal cancer were low at 1% - 2.2%. The investigators believe the results show
that monitoring without immediate treatment might be an option for some people. However, they also acknowledge that uncertainty about the reliability
of anal cytology tests makes it difficult to estimate precise rates of disease
There is a high
prevalence of anal human papillomavirus (HPV) infection among people living with HIV. Persistent infection with high-risk types of HPV can lead to
pre-cancerous and cancerous anal cell changes and, although rare, rates of anal cancer are
markedly higher in people living with HIV compared to other groups.
Diagnosis with pre-cancerous
anal cell changes can be worrying for patients. Even though treatment is
available, its best use is uncertain and it can be unpleasant.
background, investigators wished to establish a better understanding of the
natural history of high-grade pre-cancerous anal cell changes (anal intraepithelial
neoplasia, HGAIN) in the absence of treatment. They also wished to examine the effect of different levels of diagnostic accuracy (the sensitivity and specificity of anal cytology) on the likelihood that a patient diagnosed with a high-grade pre-cancerous lesion would either develop anal cancer or cease to have evidence of a high-grade lesion within two years of diagnosis.
regression rates were estimated in a model based on retrospective cohort data on 2804 people with
confirmed HIV infection and HGAIN who had at least two cyto-histological
assessments of anal cell changes during follow-up between 2001 and 2012. Study participants who progressed to
anal cancer within six months of first anal cytology were excluded from
analysis, and results were also excluded after patients underwent a first
treatment for anal intraepithelial neoplasia.
estimated the probability of disease regressing from HGAIN or progressing to
Participants in the cohort study were
followed for a median of 3.9 years and had a median of three anal cytology
assessments. A total of 74 people were diagnosed with anal cancer during
follow-up, but data for 23 of these individuals were excluded from the model because the
diagnosis was made within 180 days of their first cytology result.
Most participants (88%) were receiving antiretroviral therapy, 71% had an undetectable viral
load and 30% had a history of smoking – a known risk factor for the progression
of HPV-related disease.
Estimated rates of
disease regression were between 16.5 and 64.2
per 100 person-years of risk. The wide variation was due to assumptions
regarding the accuracy of anal cytology. Sensitivity of anal cytology to detect the presence of HGAIN was varied in the model between 47% and 89%.
The rate of
progression to anal cancer was between 0.5 and 1.3 per 100 person-years.
believe that the validity of their findings is suggested by similar rates of
spontaneous improvement among women with pre-cancerous HPV-related cervical
lesions. Moreover, earlier research
involving people living with HIV with HPV-associated high-grade squamous intraepithelial lesions found a disease regression rate of 41 per 100 person-years of
rates over two years therefore vary between 27 and 62% and rates of
progression to anal cancer are low at 1% to 2.2%, conclude the investigators. Monitoring
without immediate therapy may therefore be an option for people diagnosed