HIV and Anal Squamous Cell Carcinoma

Human Immunodeficiency Virus (HIV) has long been associated with Anal Squamous Cell Carcinoma. It is the 3rd most common cancer in patients with HIV.  

Patients at the highest risk of Anal Squamous Cell Carcinoma are men with HIV and a concurrent oncogenic HPV infection who are also men who have sex with other men (MSM). Their risk of Anal SCC is higher than the risk of an average person getting a common cancer.  

There is also noted to be an increase in incidence worldwide of Anal SCC . This is likely in part due to HIV prevalence increasing as advanced antiretrovirals are now able to give patients with well controlled HIV a near to normal life expectancy. However, these patients are then at risk of developing the long term sequelae of an immunocompromised state.  

HIV positive MSM are at 5x higher risk of ASCC than HIV negative MSM and HIV positive MSM, on screening, have up to 86% prevalence of Anal Intraepithelial Neoplasia (AIN), the dysplastic precursor to Anal SCC.  

There are many reports of HIV positive MSM having a high prevalence of High Grade AIN with some papers reporting up to a third of HIV positive MSM having High Grade AIN detected on anoscopy. Although HIV negative MSM do also have a risk of AIN, their risk is frequently reported as lower than HIV positive MSM.  

Due to their high risk profile, HIV positive MSM are regularly within screening programmes such as High Resolution Anoscopy, therefore this patient group’s AIN prevalence is widely reported in the literature. As they have the most contact with anoscopists, most studies assessing the treatment of AIN are involving HIV positive MSM. Consistently the treatment studies show that HIV positive patients are more likely to relapse after successful treatment of AIN and are more likely to have multifocal disease.  

The persistence of a immunocompromised state is likely to prevent the clearance of HPV, however, the treatment of HIV with antiretrovirals does not reduce the risk of developing Anal SCC, just having the virus itself is all it takes. Although it is possible that this will not always be the case, as more and more patients are receiving treatment and are successfully being classified as having an undetectable viral load.   

Previous viral loads and HIV treatment outcomes have been included in the mASCARA dataset, we hope that mASCARA will be able to answer some of the unanswered questions.  

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