**Abstract**

Thyroid cancer incidence has rapidly increased in high-income countries for the past 30 years. The increase in thyroid cancer cases may be due to improved diagnostic methods or exposure to unknown risk factors. Even though new thyroid cancer cases have increased, the mortality rate is relatively stable. Most thyroid cancer is differentiated thyroid cancer (DTC). Conventional management of DTC consists of near-total thyroidectomy followed by ablation therapy with radioiodine-131 (RAI). RAI was first used nearly 80 years ago to treat thyroid cancer and still plays a pivotal role in managing DTC. There are three RAI therapy options: remnant ablation, adjuvant therapy, and known disease treatments. After thyroid resection, radioactive Iodine-131 (RAI) is recommended for patients with intermediate to high risk of recurrent disease or distant metastases. Long-term follow-up is needed to detect a persistence or recurrence of the disease after initial RAI administration. RAI effectively improves treatment efficiency and reduces the risk of cancer recurrence and metastasis post-thyroid resection. Clinical outcome prediction is ultimately defined by appropriate management. This article will review some factors to consider when planning RAI therapy for DTC and subsequent surveillance after the therapy.

**Keywords:** adjuvant therapy, remnant ablation, refractory thyroid, risk- stratification, serum thyroglobulin, whole body scan
