Thyroid Cancer Genetic Testing

Cancers originate in the cells of the body, or more specifically, the genes within each cell. Genes determine how cells grow, how long they live and how they divide. When genes change or mutate, the information they convey may become garbled. In certain cases, cells can divide uncontrollably and cancer can develop.

Is Cancer Genetic?

The genes in your cells represent your inheritance from your mother and father, with each cell usually containing a gene from each of them.

Although a single “cancer gene” doesn’t exist, it is possible to pass along a mutated gene that could cause cancer. However, the majority of thyroid cancer cases are sporadic, which means they’re caused by a combination of hormonal, environmental, and personal factors — not an inherited “cancer gene.”

A Medullary Thyroid Cancer Genetic Test

Medullary thyroid cancer, the third most common form of the disease, has the most clearly defined genetic link. About 25 percent of medullary thyroid cancer cases are linked to inherited gene mutations.

An inherited mutation in the RET gene, which makes proteins that promote normal cell growth, can lead to three syndromes (MEN 2A, MEN 2B and FMTC) that increase the risk of medullary thyroid cancer.

A genetic test is available to help patients and their doctors evaluate their risk for hereditary thyroid cancer.

Is There A Genetic Test for Other Forms of Thyroid Cancer?

A 2003 study at Johns Hopkins Kimmel Cancer Center found a papillary thyroid cancer/gene mutation link. Researchers found the same mutation of the BRAF gene, in which a thymine nucleotide is replaced by an adenine, in 24 out of 25 cases of papillary thyroid cancer. Researchers say this alteration keeps the gene stuck in the “on” position, so it keeps promoting the growth and division of thyroid cells until cancer takes hold. Although no genetic test for papillary thyroid cancer is currently available, scientists are continuing to conduct research to help them develop improved tests and treatment.

Genetic Testing and Cancer Intervention

Even if a genetic test shows that you have a mutation linked to thyroid cancer, that doesn’t mean you have a “cancer gene,” or that you will definitely get thyroid cancer.

If a genetic test shows that you have a higher-than-average chance of getting thyroid cancer, you and your healthcare provider can plan appropriate preventive action. For example, some people with RET gene mutations opt to have their thyroids removed completely before the onset of thyroid cancer.

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Johns Hopkins Medical Institute Office of Communication and Public Affairs staff. (2003). Common thyroid cancer gene mutation found. Retrieved April 1, 2010, from the Johns Hopkins Medical Institute Office of Communication and Public Affairs Web site:

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