GENETICALLY ENGINEERED SUBSTANCE IMPROVES THYROID CANCER TESTING

September 24, 1997
Media Contact: Karen Infeld
Phone: (410)955-1534
E-mail:kinfeld@welchlink.welch.jhu.edu

A genetically engineered thyroid-stimulating compound may be used safely and effectively to screen for recurrence of thyroid cancer after surgery and cause fewer side effects than the traditional test, according to a national study led by two Baltimore physicians.

The study, published in the Sept. 25 issue of The New England Journal of Medicine, was led by Paul W. Ladenson, M.D., of Johns Hopkins and Bruce D. Weintraub, M.D., of the University of Maryland Medical Center. It was supported by the National Institutes of Health and includes results from Hopkins and 14 other institutions around the country.

The compound studied -- recombinant human thyroid-stimulating hormone (rhTSH) -- is a synthetic form of thyroid-stimulating hormone, a hormone produced in the pituitary gland that stimulates the thyroid to release a hormone that helps control metabolism. In the study, rhTSH facilitated accurate testing for recurrent cancer while patients stayed on their usual thyroid hormone suppression drugs. Patients currently must stop their medication for the test. This can cause temporary hypothyroidism (decreased thyroid activity), resulting in fatigue, depression and weight gain.

"This could revolutionize the way we manage the health care of patients with thyroid cancer," says Ladenson, director of endocrinology and metabolism at Johns Hopkins. "In most patients, the test quality with the synthetic compound is the same or better than with traditional hormone withdrawal and with a markedly higher quality of life for patients." Weintraub, professor of medicine at the University of Maryland School of Medicine and chief of the Laboratory of Molecular Endocrinology at the University of Maryland's Institute of Human Virology, says, "It is gratifying to see these results. We anticipate that patients will no longer have to endure the debilitating side effects of hypothyroidism in order to have sensitive testing to detect thyroid cancer."

In 1988, Weintraub and his associate, Fred Wondisford, M.D., discovered the gene for human thyroid-stimulating hormone, the key step needed for the development of the synthetic TSH and the new test.

In the new study, researchers looked at 127 people who had part or all of their thyroid gland removed because of cancer. Each patient had a test called a radioiodine scan to look for recurrence of cancer. The first scan was done while patients took both their thyroid hormone suppression drug and rhTSH. The second scan was done the traditional way, with patients taken off hormone suppression medication temporarily so the thyroid gland was reactivated to absorb the radioiodine on its own.

Results show that the scans using the artificial compound were equal to or better than the traditional method in 109 patients, or 86 percent of the study group. Of these, 106 had equal scans and three had better scans.

Results also show that patients had a better quality of life when given the artificial compound coupled with their medication than when they were taken off medication. The quality of life score measured the severity of hypothyroid symptoms, including depression, weight gain, fatigue, muscle weakness, cramps and dry skin.

The synthetic compound used in this study, Thyrogen∆, is produced by Genzyme Corp. (Cambridge, Mass.) After first cloning the TSH gene, Weintraub worked with Genzyme to create and develop Thyrogen to benefit patients.

Traditional post-operative treatment of thyroid cancer patients includes a long period of taking medication to suppress production of thyroid-stimulating hormone, which may fuel tumor growth, and periodic radioiodine scans to make sure the cancer has not returned.

Going on and off hormone-suppression therapy typically causes unpleasant symptoms that put stress on the body, including strain on the heart, as patients' thyroid hormone level falls.

About 200,000 people in the United States have thyroid cancer, with evidence that the incidence is increasing. About 1,000 Americans die from thyroid cancer each year.

Other centers involved in the study were: Beth Israel Hospital, Boston; Massachusetts General Hospital, Boston; Mayo Clinic and Foundation, Rochester, Minn.; Mount Sinai Medical Center, New York; National Institute of Diabetes and Digestive and Kidney Diseases, Bethesda, Md.; New York Hospital, Cornell Medical Center, New York; Ohio State University, Columbus; Sinai Hospital of Baltimore; University of Chicago Medical Center; University of Cincinnati Medical Center; University of Massachusetts Medical Center, Worcester; University of Miami School of Medicine; Veterans Administration Medical Center, San Francisco; and Genzyme Corp.


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