This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Which of the following is the treatment of choice in the management of carcinoma of the anal canal? 
Select and explain. 
A. Primary radiotherapy, B. Abdominoperineal resection, C. Combined radio-and chemotherapy, D. Neoadjuvant chemotherapy and local excision
C: Combined radio-and chemotherapy
Answer: C: Combined radio-and chemotherapy 
Explanation: A combination of chemotherapy and radiotherapy, so-called chemo radiation (Nigro) is the preferred initial therapy for all anal canal tumours. In such patients a combination of 5 flourouracil and mitomycin is given for approximately 1 week and chemotherapy is followed by radiotherapy, given over 3-7 weeks. Ref: Bailey and Love's Sho Practice of Surgery, 24th Edition, Pages 1269-71.