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What are the risk factors?

The cause of thyroid cancer is unknown, but some factors are known to increase the risk of developing it. Having a risk factor does not necessarily mean that you will develop thyroid cancer. Most people with thyroid cancer have no known risk factors.

Exposure to radiation – A small number of thyroid cancers are due to having radiation therapy to the head and neck area as a child, or living in an area with high levels of radiation, such as the site of a nuclear accident. Thyroid cancer usually takes 10–20 years to develop after significant radiation exposure.

Family history – Only around 5% of thyroid cancer runs in families. Having a parent, child or sibling with papillary thyroid cancer may increase your risk. Some inherited genetic conditions, such as familial adenomatous polyposis or Cowden syndrome, may also increase your risk of developing papillary thyroid cancer.  Most cases of medullary thyroid cancer do not run in families. However, some people inherit a faulty gene called the RET gene. This gene can cause familial medullary thyroid cancer (FMTC) or multiple endocrine neoplasia (MEN). If you are concerned about having a strong family history of thyroid cancer, talk to your doctor. They may refer you to a genetic counsellor or a family cancer clinic to assess your risk.

Other factors – People who are overweight or obese possibly have a higher risk of developing thyroid cancer. Other thyroid conditions, such as thyroid nodules, an enlarged thyroid (known as a goitre) or inflammation of the thyroid (thyroiditis), only slightly increase the chance of developing thyroid cancer.

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This information is reviewed by

This information was last reviewed January 2020 by the following expert content reviewers: A/Prof Diana Learoyd, Endocrinologist, Northern Cancer Institute, and Northern Clinical School, The University of Sydney, NSW; Dr Gabrielle Cehic, Nuclear Medicine Physician and Oncologist, South Australia Medical Imaging (SAMI), and Senior Staff Specialist, The Queen Elizabeth Hospital, SA; Dr Kiernan Hughes, Endocrinologist, Northern Endocrine and St Vincents Hospital, NSW; Yvonne King, 13 11 20 Consultant, Cancer Council NSW; Dr Christine Lai, Senior Consultant Surgeon, Breast and Endocrine Surgical Unit, The Queen Elizabeth Hospital, and Senior Lecturer, Discipline of Surgery, University of Adelaide, SA; A/Prof Nat Lenzo, Nuclear Physician and Specialist in Internal Medicine, Group Clinical Director, GenesisCare Theranostics, and The University of Western Australia, WA; Ilona Lillington, Clinical Nurse Consultant (Thyroid and Brachytherapy), Cancer Care Services, Royal Brisbane Women’s Hospital, QLD; Jonathan Park, Consumer.