Thyroid cancer is rapidly increasing in incidence, but the mortality rate remains flat. Debate has arisen over the need to detect or treat most thyroid cancers early, given their favorable natural history. The appropriate extent of surgery for thyroid cancer is also controversial: some researchers advocate partial and others total thyroidectomy; some advocate prophylactic central cervical lymph node dissection, whereas others only rarely recommend lymphadenectomy. Although radioactive iodine is effective, its appropriate use and dosage remain controversial. In addition, molecular analysis of thyroid cancer is frequently used for diagnostic purposes involving preoperative fine-needle biopsy specimens as well as to define targetable pathways altered in the disease to guide clinical trials of drug therapy for advanced thyroid cancers.