This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Thyroid Malignancies, Subject name: Surgery
[{'content': 'Which iodine isotope is used for treatment of carcinoma of thyroid? \nSelect and explain. \nA. Iodine 131, B. Iodine 123, C. Iodine 213, D. All of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ans. (a) Iodine 131Ref: Bailey & Love 26th ed. / 768The initial treatment for cancer of the thyroid is surgical. A consensus approach might be to perform a total thyroidectomy if the primary tumor is larger than 1 cm in diameter or if there is extra-thyroidal involvement or distant metastases. Clinically evident lymphadenopathy should be removed with a neck dissection. If the primary tumor is less than 1 cm in diameter, a unilateral lobectomy might be considered. About 4-6 weeks after surgical thyroid removal, patients must have radioiodine to detect and destroy any metastasis and any residual tissue in the thyroid', 'role': 'assistant'}]