Thyroid cancer happens because of mistakes in genes in the cells of your thyroid gland. These mistakes, sometimes called gene mutations or alterations, allow cells to grow, multiply, and become abnormal.

If you have thyroid cancer, your doctor might tell you that it’s “RET-altered.” This means an error in the RET gene is a cause.

What Is the RET Gene?

Normally, the RET gene tells your body to make a protein that helps certain nerve cells develop. This protein is also important for healthy kidneys and a man’s sperm production.

You’re born with two copies of the RET gene that you receive at random from each of your parents. If you inherit a mutation of one copy of the RET gene, it can raise your chances of having certain cancers.

With each pregnancy, there’s a 50% chance that an affected parent will pass this abnormal gene to a child.

But some people get an RET mutation even if they don’t inherit the gene defect.

What Types of Thyroid Cancers Can the RET Gene Affect?

There are two types of gene mutations:

  • Inherited: You’re born with this type. It’s found in every cell in your body.
  • Somatic: You pick up a somatic alteration during your lifetime. These mutations don’t appear in every cell in the body.

Cancers that happen because of somatic mutations are called sporadic cancers, and they’re much more common than inherited, or hereditary, ones.

Scientists have identified somatic RET gene mistakes in papillary thyroid cancers and a form of medullary thyroid cancer that doesn’t run in families.

An inherited RET gene mutation can also cause a type of medullary thyroid cancer that’s passed on from a parent. Those who are born with this gene defect almost always get medullary thyroid cancer.

Research shows an altered RET gene in about 63% of people with all types of medullary thyroid cancer. For those with papillary thyroid cancer, it’s between 10% and 30%.

What’s the Difference Between Papillary and Medullary Thyroid Cancers?

Papillary thyroid cancers happen in the follicular cells. These are the cells that make and store thyroid hormones. They’re the most common type of thyroid cancer. In fact, about 80% of thyroid cancers are this type. 

They usually grow slowly and affect only one lobe of the thyroid gland. Papillary thyroid cancers are usually very treatable, even if they spread.

Medullary thyroid cancers start in thyroid cells called C cells, which make the hormone calcitonin. They’re rare and account for only about 4% of thyroid cancers.

This type can spread to the lymph nodes, lungs, or liver even before you notice a thyroid lump. Medullary cancers can be inherited or sporadic.

Unlike papillary thyroid cancer, the medullary type is generally hard to identify and treat.

What Other Diseases Is the RET Gene Linked To?

In addition to papillary and medullary thyroid cancers, scientists have also linked an RET gene mutation to a condition called multiple endocrine neoplasia type 2 (MEN2). This hereditary disorder makes you more likely to have different types of tumors, such as thyroid tumors. In fact, if you have MEN2, your risk of medullary thyroid cancer is nearly 100%.

Should You Be Screened for an RET Mutation?

If you have a strong family history of thyroid cancer, your doctor might recommend that you have a screening test for an RET alteration.

A blood test is typically used to identify a faulty RET gene.

You can choose whether to have the test or not. Not everyone wants to know if they have this mutation.

Even if you don’t get a genetic test, blood tests or thyroid ultrasounds may help doctors identify the cancer at an early stage.

WebMD Medical Reference

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