Radiation therapy in anal and rectal cancer.

Historically, squamous cell carcinoma of the anal canal was treated with abdominoperineal resection. Nigro discovered that radiation therapy combined with 5-fluorouracil and mitomycin resulted in high rates of local control and colostomy-free and overall survival without surgical intervention. Recent advances include the integration of PET into staging, radiation treatment planning, disease monitoring, and the use of intensity-modulated radiation therapy. For rectal cancer, clinical trials have established the role for neoadjuvant therapy for T3-4 and/or node-positive tumor presentations. Chemotherapy and targeted agents are under study in both anal and rectal cancers to improve on the standard combinations of chemotherapy and radiation.