Final answer:
Thyroid cancer with a poor prognosis and potential to spread to lungs and bones is treated with radioiodine therapy, particularly Iodine-131. This treatment leverages the thyroid's natural ability to concentrate iodine, allowing targeted imaging and therapy. However, care must be taken to minimize damage to other organs involved in elimination of radiopharmaceuticals.
Step-by-step explanation:
Radioiodine Therapy and Prognosis in Thyroid Cancer
Thyroid cancer that has a poor prognosis and can metastasize to the lungs or bones is often treated with radioiodine therapy, especially when the disease is unresectable or has spread significantly. Radioactive iodine, particularly Iodine-131 (I-131), is selectively absorbed by the thyroid cells, including the cancerous ones which are typically more aggressive in concentrating iodine. This trait of thyroid cells is utilized in both imaging and treatment of thyroid disorders. I-131 therapy targets cancerous thyroid tissue effectively, often with radioactive iodine being administered to image or irradiate areas affected by metastases.
In addition to its direct cytotoxic effects on thyroid cancer cells, I-131 imaging is also applied to detect the spread of thyroid cancer to other organs by identifying areas of iodine uptake signaling metastatic disease. However, the efficient localization and high therapeutic ratio of I-131 are somewhat offset by the potential risks posed to other organs that eliminate radiopharmaceuticals, such as the liver, kidneys, and bladder. Therefore, the use of radiopharmaceuticals in cancer therapy must maintain a balance between damaging cancer cells and sparing normal tissue.