Anal Canal Cancer: Pathophysiology, Diagnosis and Treatment

Abstract

Anal cancer is a rare malignancy accounting for 2.5 % of all digestive system malignancies in the United States. Squamous cell carcinoma is the most common histological variant comprising of 80–90 % of all anal cancer cases. Spread is by local extension and lymphatic pathways. The size of primary tumor and lymph node metastasis are the most important prognostic indicators. The primary goal of treatment is eradication of tumor with organ preservation. Abdomino-perineal resection with permanent end-colostomy, which was the standard definitive treatment for anal canal cancer in the past, is now reserved for residual or recurrent cancer. Combined modality treatment (CMT) comprising of radiotherapy and chemotherapy to preserve sphincter function is the preferred standard therapy for treatment of anal cancer. Chemoradiation itself has undergone remarkable development in the bygone years and various trials have determined the optimal radiation dose, fractionation and chemotherapeutic regimen. Definitive chemoradiation with concurrent 5-fluorouracil and Mitomycin-C is the established treatment in patients with anal cancer as confirmed by various trials.