Staging and Initial Evaluation of Anal Cancer

Abstract

Anal cancer commonly presents with rectal bleeding, pain, and mass sensation, although these are frequently mistaken for benign anal pathology leading to a delay in diagnosis. As the treatment of anal cancer is nonsurgical, anal cancer is clinically staged with an emphasis on physical examination, focusing on digital rectal exam (DRE), inguinofemoral lymph node evaluation, and gynecologic exam in female patients. Anoscopy or proctoscopy with biopsy confirms the diagnosis and histological type. Biopsy of suspicious inguinal nodes should be considered if indeterminate on clinical or radiographic assessment. Screening for human immunodeficiency virus (HIV) in all patients and for cervical cancer in females is generally performed, while prostate-specific antigen (PSA) screening in males and colonoscopy are optional. Proper staging workup includes computed tomography (CT) or magnetic resonance imaging (MRI) of the pelvis and CT of the chest and abdomen. The addition of whole-body positron emission tomography-computed tomography (PET/CT) leads to further nodal evaluation and informs radiotherapeutic treatment planning for curative cases. Anal canal cancers, located between the anorectal junction and the anal verge, and perianal cancers, located within 5 centimeters of the anal verge, are staged together using the American Joint Committee on Cancer (AJCC) classification scheme. About one-half of patients present with localized disease and another one-third present with regional lymphadenopathy, with the remainder found to have distant metastases.