Hi, Use of Radio active iodine is effective against many toxic or overactive nodules of thyroid. It is also effective against many types of thyroid cancers- particularly papillary and follicular thyroid cancers, which arise from the follicular cells of thyroid as follicular cells of thyroid absorb iodine. When radio active iodine is given to a patient of thyroid cancer, it is taken by the cancerous cells and destroys them including those cancerous cells, which have spread to the lymph nodes or other parts of the body. Though, it is not effective against medullary and anaplastic thyroid cancers, as they do not absorb iodine. Even after surgery of papillary or follicular thyroid of cancer, this may be given after the surgery to prevent the recurrence. Being papillary cancer, in your case, it may be definitely effective. However, you are advised to follow the directions of your doctor in this case, as he is always in a position to make a better decision, taking your clinical condition into consideration. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Satnarain Bansal, General & Family Physician