An unpleasant postoperative procedure for
thyroid cancer patients who have had their thyroid glands surgically removed may be unnecessary for most patients, according to
Washington University researchers at Siteman
Cancer Center and Barnes-Jewish Hospital in St. Louis.
Physicians have long assumed that early follow-up scans for residual or recurrent thyroid cancer are only possible when patients have been through six weeks of a weaker thyroid medication and two to three weeks of no thyroid medication.
Withdrawal from medication leads patients' bodies to produce their own thyroid-stimulating hormone (TSH), and exposure to sufficiently high levels of TSH creates an increased thirst for iodine in any remaining thyroid cells. Scientists can then give patients small doses of radioactive iodine that will be taken up by the cells. A weaker dose lets scientists detect the cells; a stronger dose kills them.
In a study published in the April issue of The Journal of Nuclear Medicine, Washington University School of Medicine scientists report that simply taking patients off thyroid medication for two weeks prior to the scan produces the desired changes in nearly 90 percent of patients.
"When patients are taken off thyroid medication, they get tired, gain weight and just generally don't feel very good," says lead investigator Perry W. Grigsby, M.D., professor of radiology and of radiation oncology. "We don't want patients to feel bad, so we want them to be off medication for as short a time as possible."
Physicians diagnose an estimated 14,000 new cases of thyroid cancer per year, with women developing the cancer at rates two to three times those of men. Located in the neck, the thyroid gland regulates metabolism through the production of thyroid hormone, which affects cell activity levels throughout the body.
Treatment of a cancerous thyroid generally begins with surgical removal of the gland. To compensate, patients take thyroid medication for the rest of their lives.
In early postoperative scans, increased risk of recurrent or residual tumors limits physicians' options for preparing patients for those scans, according to Grigsby.
"The classic procedure is to put the patient on a weaker thyroid medication for six weeks and then take them off medication entirely for two to three weeks," Grigsby explains.