Cajas-Monson LC, et al. - In this retrospective cohort study, authors quantified aspects of high-grade squamous epithelial lesion/anal squamous cell carcinoma clinical evolution in a surgical practice. For this purpose, consecutive patients with high-grade squamous intraepithelial lesion and anal squamous cell carcinoma were analyzed and a comparison group of HIV-positive patients presenting de novo with anal squamous cell carcinoma (no prior history of high-grade squamous intraepithelial lesion) was reviewed. For high-grade squamous intraepithelial lesions, both ablation and expectant management have been proposed. Outcomes revealed approximately 1% per patient-year progression of untreated high-grade squamous intraepithelial lesion to anal squamous cell carcinoma. Relatively fewer major interventions were required for anal squamous cell carcinoma developing under surveillance that tends to be of an earlier stage than anal squamous cell carcinoma presenting de novo. Lower cancer-specific mortality was noted for malignancies that developed under surveillance. Expectant management of patients with high-grade squamous intraepithelial lesion was thus suggested to be a rational strategy for preventing anal cancer morbidity.