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
[{'content': 'A 1 cm x 1 cm squamous cell carcinoma of anal canal is best treated initially by \nSelect and explain. \nA. Abdominoperineal resection, B. Localized resection followed by irradiation, C. Proximal colostomy followed by interstitial irradiation, D. Chemo-radiotherapy', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Anal cancer: #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', 'role': 'assistant'}]