Anal cancer is a rare malignancy, with a global incidence of approximately 1.5 per 100,000 people, accounting for less than 2% of all gastrointestinal cancers. However, its incidence has been rising in recent years. Most cases are squamous cell carcinomas (SCC), strongly linked to human papillomavirus (HPV), particularly HPV-16.

Other risk factors include receptive anal intercourse, multiple sexual partners, smoking, immunosuppression, such as in individuals infected with the human immunodeficiency virus (HIV), as well as a history of cervical, vaginal, or vulvar cancer.

Imaging plays a crucial role in diagnosing, staging, and planning treatment for anal cancer. The diagnostic work-up typically includes proctoscopy with biopsies, pelvic MRI, ultrasound with fine needle aspiration for inguinal lymph nodes, and computed tomography (CT) or fluorodeoxyglucose positron emission tomography (FDG-PET) to detect further nodal and distant metastasis.

MRI is the preferred modality for evaluating anal carcinoma, offering superior soft tissue contrast and detailed visualization of tumor extent and involvement of adjacent structures. High-resolution T2-weighted (T2W) and diffusion-weighted imaging (DWI) sequences are particularly valuable for delineating tumor boundaries and assessing lymph node involvement. 

Chemoradiotherapy (CRT) is the standard treatment, achieving complete remission in 80-90% of patients. Surgery is required for those with residual tumors.