Side Effects of Cancer Treatment
Because cancer treatment may damage healthy cells and tissues, unwanted side effects sometimes occur. These side effects depend on many factors, including the type and extent of the treatment. Side effects may not be the same for each person, and they may even change from one treatment session to the next.
Surgery. Patients are often uncomfortable for the first few days after surgery. However, medicine can usually control their pain. Patients should feel free to discuss pain relief with the doctor or nurse. It is also common for patients to feel tired or weak. The length of time it takes to recover from an operation varies for each patient.
After surgery to remove the thyroid and nearby tissues or organs, such as the parathyroid glands, patients may need to take medicine (thyroid hormone) or vitamin and mineral supplements (vitamin D and calcium) to replace the lost functions of these organs. In a few cases, certain nerves or muscles may be damaged or removed during surgery. If this happens, the patient may have voice problems or one shoulder may be lower than the other.
Radioactive Iodine (I-131) Therapy. Some patients have nausea and vomiting on the first day of I-131 therapy. Thyroid tissue remaining in the neck after surgery may become swollen and painful. If the thyroid cancer has spread to other parts of the body, the I-131 that collects there occasionally may cause pain and swelling.
Patients also may have a dry mouth or lose their sense of taste or smell for a short time after I-131 therapy. Chewing sugar-free gum or sucking on sugar-free hard candy may help at the time of I-131 administration may help prevent this.
During treatment, patients are encouraged to drink lots of water and other fluids. Because fluids help I-131 pass out of the body more quickly, this reduces the bladder's exposure to I-131.
Because radioactive iodine therapy destroys the cells that make thyroid hormone, patients may need to take thyroid hormone pills to replace the natural hormone.
A rare side effect in men who received large doses of I-131 is loss of fertility. In women, I-131 may not cause loss of fertility, but some doctors suggest that women avoid pregnancy for six months to one year after I-131 therapy.
Researchers have reported that a very small number of patients may develop leukemia years after treatment with high doses of I-131.
Follow-up care after treatment for thyroid cancer is an important part of the overall treatment plan. Regular checkups ensure that any changes in health are noted. Problems can be found and treated as soon as possible. Checkups may include a careful physical exam, x-rays and other imaging tests (such as a nuclear medicine iodine scan), and laboratory tests.
An important laboratory test after thyroid cancer treatment measures the level of thyroglobulin in the blood. Thyroid hormone is stored in the thyroid as thyroglobulin. If the thyroid has been removed, there should be very little or no thyroglobulin in the blood. A high level of thyroglobulin may mean that thyroid cancer cells have returned.
For three to six weeks before the thyroglobulin test, patients must stop taking their usual thyroid hormone pill. For part of this time, some patients may take a different, shorter-lasting thyroid hormone pill. But all patients must stop taking any type of thyroid hormone pill for the last two weeks right before the test. Without adequate levels of thyroid hormone, patients are likely to feel uncomfortable. They may gain weight and feel very tired. After the test, patients go back to their usual treatment with thyroid hormone pills.
The doctor may request an I-131 scan of the entire body. This may be called a "diagnostic I-131 whole body scan." For a short time (usually three to six weeks) before this scan, the patient stops taking thyroid hormone pills. Thyroid cancer cells anywhere in the body will show up on the scan. After the test, the doctor will tell the patient when to start taking thyroid hormone pills again.