ATA News Release 2004

Dietary supplement may be future treatment for thyroid cancer

(VANCOUVER, BC, Oct. 1, 2004)—The well-tolerated dietary supplement selenium significantly reduces thyroid cancer cell growth when studied in culture, according to new research being presented on Friday, Oct. 1, at the 76th Annual Meeting of the American Thyroid Association in Vancouver, British Columbia, Canada. Researchers say that future studies addressing the role of selenium in the treatment and prevention of thyroid cancer are warranted based on these findings.

Selenium is an essential trace mineral that is involved in multiple enzymatic and cell regulatory roles in the body. It is an essential part of many antioxidants and catalysts. Integral to the immune system, selenium supplementation has been shown to decrease the progression of HIV and also reduce the risk of developing prostate cancer. Several clinical trials are underway to uncover selenium’s role in cancer prevention.

Researchers at Weill Cornell Medical College/New York-Presbyterian Hospital in New York City wanted to explore this issue using microarray analysis. Microarray is a powerful tool that provides information about the genetic changes occurring in cancer cells as well as those changes seen after medical treatment. This information can then be used to direct clinical research and aid in the fight on cancer.

Working in the lab of Thomas J. Fahey, MD, David J. Finley, MD, a Clinical Research Fellow, used an in vitro model of follicular, papillary, and anaplastic thyroid cancer. Each cell line was treated with three different doses of selenium. They found that growth of all three thyroid cancer cell lines was inhibited by selenium in a dose-dependent manner. They also found that selenium works by turning on a group of genes — Growth Arrest and DNA Damage inducible genes (GADD) — that function as cell cycle regulators.

“GADD genes modulate growth and division of cells by arresting them in part of the cell cycle,” explained Dr. Finley. “This essentially causes the cells to no longer have the ability to divide, thus stopping the growth of cancer cells.”

He added, “The results of this study can elucidate possible genetic events that lead to thyroid cancer and may help direct treatment in the future. Our data need to be translated into human trials to see the effects of selenium supplementation on thyroid cancer cell growth in real-life situations.”

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