Some types of thyroid cancers are known to be hereditary, but genetics aren’t the only cause.

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A variety of factors can contribute to someone developing many of the most commonly known cancers. Yet, some tend to be more closely linked with genetics than others.

If you have a family history of thyroid cancer or have a known thyroid issue, it’s important to know more about your risk of developing thyroid cancer and what preventive tests can help you detect it early if you have it.

There are several possible causes of thyroid cancer — one of them is having a family history of cancer.

Specifically, having a close relative like a parent or sibling that has had thyroid cancer can increase your chances of also being diagnosed with this condition.

This is not the same as saying you have an inherited syndrome or are genetically predisposed to have thyroid cancer.

Thyroid cancer and hereditary conditions

Some types of thyroid cancer have a closer link to genetics.

For example, medullary thyroid cancer is sometimes caused by an abnormal gene. Formally known as familial medullary thyroid carcinoma (FMTC), roughly 2 out of 10 medullary thyroid cancers are because of a genetic abnormality. But often, people with this type of cancer develop it in childhood or early adulthood.

Other medical conditions that might increase a person’s chance of developing thyroid cancer include:

What percentage of thyroid cancer is genetic?

There are multiple forms of thyroid cancer, so as a result, genetic links for each type can vary widely.

As a whole, only 5% of all thyroid cancers are thought to be genetic. For nonmedullary thyroid cancer, 5–15% of cases are connected with known genetic causes.

Other causes of thyroid cancer

Family history isn’t the only reason a person might develop thyroid cancer. Exposure to radiation is also a serious factor. However, this refers to sustained exposure — not the occasional X-ray.

In most cases, a person must have sustained large doses, especially at a younger age, to increase their risk of developing thyroid cancer later on. For example, children treated with radiation therapy for other cancers might face an increased risk for thyroid cancer because of sustained exposure.

Having an iodine deficiency or obesity or overweight may also increase your chances of being diagnosed with thyroid cancer.

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If you know that you have a family history of thyroid conditions or cancer, you may want to consider genetic testing to assess your risks.

A variety of tests exist to not only determine if you have a higher chance of developing cancer but also to confirm the right treatment methods to avoid overtreatment.

Because thyroid cancer is often linked with excessive radiation exposure, many experts are looking for imaging diagnostic alternatives. Instead, genomic reviews that look for abnormalities in thyroid tissue samples can be very effective in determining if further diagnostics are needed.

However, more traditional genetic testing methods can include:

  • polymerase chain reaction (PCR) to identify genetic mutations
  • Sanger dideoxy sequencing to look for nucleotide variants in the DNA sequence
  • multiplex ligation-dependent probe amplification (MLPA) — a type of PCR test — looks for isolated mutations of a single nucleotide
  • fluorescence in situ hybridization (FISH) tags DNA sequences with fluorescent probes to detect chromosomal and genetic abnormalities
  • next-generation sequencing — a rapid sequence test for entire genomes — can be a cheaper alternative

Who should be tested for thyroid cancer?

Unlike other cancers, there isn’t a standard timetable for routine testing if you have an average or low risk of developing thyroid cancer.

If you have a family history of thyroid cancer, such as medullary thyroid cancer, your doctor will usually encourage you to get tested — even at a young age.

Even if you don’t get genetic testing, opting for a blood test or thyroid ultrasound can also aid in early detection, which increases your chances of achieving remission.

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If you experience any of the following early signs or symptoms, you should speak with a healthcare professional to get checked out immediately:

Only roughly 5% of all forms of thyroid cancers are linked with a genetic predisposition. But if you have a family history of thyroid cancer or were exposed to sustained radiation, you have a higher chance of potentially developing it.

Anyone with a family history of thyroid cancer is encouraged to do genetic testing, usually at a younger age. However, blood tests and ultrasounds are also effective tools for catching thyroid cancer early.

If you have any symptoms or signs of thyroid cancer, contact a doctor immediately to get checked out.