This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Surgery
The preferred initial treatment for carcinoma of the anal canal is 
Select and explain. 
A. Abdominoperineal resection, B. Abdominoperineal resection followed by radiotherapy, C. Radiotherapy alone, D. Chemoradiation
D: Chemoradiation
Answer: D: Chemoradiation 
Explanation: #Treatment is by chemoradiotherapy in the first instance # Associated with HPV # More prevalent in patients with HIV infection # May affect the anal verge or anal canal # Lymphatic spread is to the inguinal lymph nodes # Uncommon tumour, which is usually a squamous cell carcinoma # Major ablative surgery is required if the above fails Ref: Bailey & Love&;s Sho Practice of Surgery,E25,Page-1269