Harnessing the Microbiota to Discover Biomarkers of Precancerous Anal Lesions in People with HIV. SCRAtCH -Microbiota-based SCReening of Anal Cancer in HIV-infected individuals

The risk of anal cancer is markedly increased (40–130 fold) in HIV-infected subjects, especially among men who have sex with men (MSM) and in women with history of anogenital HPV disease. The current screening strategy is based on the detection of highdegree squamous intraepithelial lesions (HSIL), a cancer precursor, using anal cytology. While this approach is highly sensitive, the specificity is poor, leading to an excess number of invasive procedures, explaining the poor implementation of this screening strategy. Emerging evidence supports that epithelial-adherent bacteria amplify HPV-associated cancers and contribute to impairment of mucosal immunity since the early stage of HIV-infection Hypothesis. The diagnostic value of the anal cytology for the diagnosis of HSIL can be improved by measuring bacterial biomarkers derived from anal cytologies. Aims. Primary: to identify in HIV-infected MSM a set of anal-associated bacterial biomarkers to improve the accuracy of anal cytology for the diagnosis of biopsy-proven HSIL.