Answer:
Radioactive iodine (RAI) is also known as I131 and is a type of radioisotope treatment. Radioisotopes are radioactive substances given in a pill that you swallow. Although RAI spreads through the body, it is mainly absorbed by thyroid cells or thyroid cancer cells.
People who have had RAI therapy may have a slightly increased risk of developing leukemia, stomach cancer, and salivary gland cancer in the future. Doctors disagree on exactly how much this risk is increased, but most of the largest studies have found that this is an extremely rare complication.