Routine thyroid cancer procedure may shortened

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Routine thyroid cancer procedure may shortened

Last Updated: 2004-04-09 13:05:37 -0400 (Reuters Health)

By Amy Norton

NEW YORK (Reuters Health) - A standard post-surgery routine that can

leave thyroid cancer patients feeling run-down for weeks may be largely

unnecessary, new research suggests.

The procedure, widely used for decades, calls for patients who have had

their cancerous thyroid glands removed to go off of their normal hormone

replacement therapy for six to eight weeks so that they can receive

follow-up care.

But in the new study, researchers found that just two weeks off of

thyroid replacement was sufficient for about 90 percent of the 284

patients they assessed.

This shortened time frame could cut the amount of time that patients

suffer the side effects of stopping their normal hormone replacement

therapy, according to the study authors.

The thyroid is a gland in the neck that secretes hormones that help

regulate metabolism. When thyroid hormone levels drop too low, a

condition called hypothyroidism, metabolism slows, and symptoms such as

fatigue, poor memory, weight gain and depression set in. So when the

gland is removed due to cancer, patients must take synthetic replacement

hormones for life.

However, doctors have to temporarily stop patients' replacement therapy

to give them radioactive iodine. Because the thyroid gland absorbs

nearly all of the iodine that enters the body, radioactive iodine can be

used to destroy cancerous thyroid cells. Alternatively, iodine can be

given in a small amount to reveal on X-rays any residual cancer

remaining after surgery.

When patients stop their hormone replacement, the brain produces more

thyroid-stimulating hormone (TSH), which causes any remaining thyroid

cells in the body to become " really hungry for iodine, " Dr. W.

Grigsby, the study's lead author, explained.

So once TSH levels are high enough, any thyroid cells remaining after

cancer patients' surgery will soak up the radioactive iodine. Doctors

have traditionally thought that to get this TSH elevation, patients have

to reduce thyroid medication levels for four to six weeks, then go off

hormone replacement completely for two weeks.

The problem is that this sends them into weeks of what Grigsby called

" profound " hypothyroidism. " They feel really lousy, " he told Reuters

Health. " They're tired, worn out. "

To minimize the time that patients go through this misery, Grigsby and

his colleagues at Washington University School of Medicine in St. Louis

have relied on simply stopping patients' thyroid hormone therapy for two

weeks.

Their study, reported in the Journal of Nuclear Medicine, reviewed the

records of 284 of these patients. It found that nearly 90 percent had

sufficiently high TSH levels after about two weeks off of their

medication.

According to Grigsby, the standard, six- to eight-week routine arose

from a recommendation made several decades ago that was essentially

based on logic rather than scientific evidence. The rationale was that

giving patients a weaker thyroid medication for several weeks would

allow the body to clear the hormone--and boost TSH levels--more quickly

once the medication was stopped.

But the approach has not been backed up by evidence. " I think it's been

basically a medical myth, " Grigsby noted.

In contrast, he said he thinks there is sufficient science to support

his team's abbreviated tactic. Two other recent studies, he and his

colleagues note, have also shown that at least 90 percent of patients

reach the needed TSH level after two to three weeks off of hormone

replacement.

SOURCE: Journal of Nuclear Medicine, April 2004.

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