Thyroid cancer diagnoses are increasing globally, with women nearly three times more likely to develop the disease than men. In 2021, the world saw 249,538 new cases, with 167,237 in females and 82,301 in males.While the exact causes remain unknown for many, specific risk factors like radiation exposure and family history significantly raise a person's chances of developing this cancer.The average age for diagnosis is 51 years, younger than for most other adult cancers.[pmc+6]
Understanding the Thyroid and Cancer's Rise
The thyroid is a butterfly-shaped gland in the front of your neck, below the voice box.It is part of the endocrine system, making hormones that control vital body functions like heart rate, blood pressure, temperature, and metabolism.Cancer starts when DNA in thyroid cells changes, or mutates.Most mutations happen over time, but some are passed down from parents.[hackensackmeridianhealth+5]
The incidence of thyroid cancer has risen over recent decades. In the United States, diagnoses more than tripled since the 1990s, partly due to more widespread use of imaging tests like ultrasounds.These tests can find small cancers that might not have caused problems otherwise.However, increases in advanced-stage cases also suggest other factors are at play.[pmc+6]
Key Risk Factors Identified by Experts
Several factors increase a person's risk for thyroid cancer. One of the strongest is exposure to radiation, especially during childhood.This includes radiation therapy for other cancers in the head and neck area, or exposure to radioactive fallout from nuclear accidents or weapons.The risk grows with larger radiation doses and younger age at exposure.Doctors now try to limit radiation to the head and neck unless absolutely necessary, using shields during X-rays and CT scans.[cancerresearchuk+17]
Genetics also play a major role. You have a higher risk if a close family member, such as a parent, sibling, or child, has had thyroid cancer.Certain inherited conditions, like Multiple Endocrine Neoplasia type 2A (MEN2A) or 2B (MEN2B), Cowden syndrome, and familial adenomatous polyposis (FAP), are directly linked to an increased risk.For example, MEN2 greatly increases the risk of medullary thyroid cancer, and family members can be tested for the mutated gene.[my+12]
Women are three times more likely to get thyroid cancer than men.It is most common in women in their 40s and 50s, while men are typically diagnosed in their 60s and 70s.The reasons for this difference are still unclear, but researchers are studying links to hormones, pregnancy, and birth control.[my+7]
Other risk factors include being overweight or obese, which increases the risk of thyroid cancer.Some non-cancerous thyroid conditions, such as an enlarged thyroid gland (goiter), Hashimoto's disease, or certain thyroid nodules, can also slightly increase risk.Iodine intake can also be a factor; low iodine diets may raise the risk of follicular thyroid cancer, while high iodine intake might increase the risk of papillary thyroid cancer.[my+13]
Types of Thyroid Cancer
Thyroid cancers are classified by the type of cells they grow from.[my+1]
- Papillary thyroid cancer is the most common, making up 70% to 90% of all thyroid cancers. It usually grows slowly and often spreads to nearby lymph nodes in the neck. However, it responds very well to treatment and is highly curable.
- Follicular thyroid cancer accounts for 10% to 15% of diagnoses. It is more likely to spread to bones and organs like the lungs, but treatment often leads to a good outlook.
- Medullary thyroid cancer makes up less than 5% of cases. About a quarter of people with this type have a family history, often linked to a faulty gene. It is more aggressive than papillary or follicular types.
- Anaplastic thyroid cancer is rare, accounting for about 1% to 2% of diagnoses, but it is very aggressive and difficult to treat. It grows and spreads quickly.
The initial sign of thyroid cancer is often a painless lump, or nodule, in the neck.However, most thyroid nodules are not cancerous; only about 1 in 10 turn out to be cancer.Other possible symptoms include neck swelling, swollen lymph nodes, hoarseness, trouble breathing or swallowing, or a persistent cough not caused by a cold.Many thyroid cancers are found incidentally during unrelated medical procedures or imaging.[my+17]
What You Can Do
While preventing most thyroid cancers is not possible because the exact causes are often unknown, you can take steps to reduce your risk.Limiting unnecessary radiation exposure to the head and neck, especially during childhood, is crucial.Maintaining a healthy body weight through a balanced diet and regular exercise also helps lower risk.[pennmedicine+7]
Knowing your family's medical history for thyroid cancer or related genetic conditions is important.Regular self-checks of your neck for lumps or nodules and discussing any concerns with your doctor can aid in early detection.Early detection is vital for many cancers, and thyroid cancer is often highly treatable when found early.[cancer+6]
