Dr. Varma discovered that Rev. Barnes' cancer was growing agressively in spite of the therapy received in Wisconsin and recommended a higher dose of radioactive iodine treatment. More than a century ago, it was discovered that thyroid cells have a unique ability to absorb iodine. Iodine is found in the bloodstream as a byproduct from many of the foods we eat like milk, shellfish, iodized salt, and in preservatives in processed food. The thyroid needs the iodine to produce the thyroid hormone that regulates the body's metabolism. Because of the thyroid's unique absorption of iodine, a chemotherapy for thyroid cancer is possible.
Radioactive iodine is given as a drink along with water.
The iodine enters the bloodstream and is absorbed by the thyroid cells. Then, the radioactivity kills all the thyroid cells, including the cancerous ones, from within. Since all other tissues in the body do not significantly absorb iodine, they are not harmed by the radioactivity. For Rev. Barnes, receiving the therapy meant a two-day stay in the hospital. By hospitalizing him, doctors were able to isolate him from contact with other people.