Updated project metadata. Anal squamous cell carcinoma (ASCC) is an infrequent tumor. Since 70s, treatment of stages II-III consists on a combination of 5-fluorouracil (5FU), mitomycin C (MMC), and radiotherapy. The aim of this study is the identification of biomarkers that allow personalized treatment and improvement of therapeutic outcomes. Forty-six tumor paraffin samples from ASCC patients were analyzed by whole-exome sequencing. Single nucleotide polymorphisms and copy number variants (CNVs) were identified and their relation to disease-free survival (DFS) was studied using BRB Array Tool and Kaplan-Meier analyses. Obtained findings were validated in an independent retrospective cohort of 101 ASCC patients with stages I-III from eleven hospitals within the Multidisciplinary Spanish Digestive Cancer Group (GEMCAD) using qPCR Copy Number Assays. GEMCAD validation cohort was also analyzed using mass spectrometry proteomics to assess the biological features of these tumors.