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.

For the study, Grigsby and colleagues closely monitored the TSH levels in nearly 300 thyroid cancer patients whose thyroids had been removed and who were not taking medication. Some of the patients were just out of surgery and hadn't yet started taking the hormone; others were taken off the hormone without the standard six-week period on the weaker form of the drug. Researchers found that 89 percent of the group had achieved the TSH level needed for postoperative imaging in one to two weeks. By the third week, 96 percent were at or beyond the desired level.

"We don't seem to need six weeks on the less effective medication," Grigsby says. "That approach appears to have originated as someone's best guess as to what we needed to do to prepare patients for scans, and no one ever questioned it. But now we know we can do it in a way that is simpler, quicker and above all easier on patients."

Grigsby notes that the introduction of recombinant human thyroid-stimulating hormone (rhTSH) five years ago greatly reduced the need to take patients off thyroid medication for later follow-up scans. The body responds to rhTSH in the same way it responds to cessation of thyroid medication, making it possible for scientists to scan for cancer cells.

However, rhTSH can also complicate and delay treatment of tumors, so physicians generally do not use it in the earliest postoperative scans, when odds of finding tumors again are highest.

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Contact: Michael C. Purdy
purdym@wustl.edu
314-286-0122
Washington University School of Medicine
30-Mar-2004