Many patients with thyroid cancer have no symptoms whatsoever. A lump on the thyroid gland may be found by chance on a routine physical exam or an imaging study of the neck done for unrelated reasons. Other patients feel a gradually enlarging lump in the front portion of the neck or have difficulty swallowing or speaking. Occasionally, the lump may cause a feeling of pressure or shortness of breath. Finding a lump in the neck should be brought to the attention of your physician, even in the absence of symptoms.
Causes and Risk Factors
The exact reason nodules grow in the thyroid gland is not known. But these factors increase the risk:
- Family History. If a parent or sibling had a thyroid nodule, the chance of developing a nodule is increased
- Age. The risk of developing a nodule increases as you age.
- Gender. Woman develop nodules more often than men
- Thyroiditis. Nodules are more likely to form in people who have chronic inflammation of the thyroid gland.
- Radiation exposure to the head or neck. Babies, children and teenagers were treated with radiation for birthmarks, acne or enlarged tonsils in the 1940s and 1950s. People who had these treatments have an increased risk. Exposure to nuclear power plant accidents (for example, the 1986 nuclear power plant explosion in Cherynobyl), or radioactive particles released into the air during atomic weapons testing also increases the risk.
Thyroid Cancer Types
- Papillary thyroid cancers account for about 80 to 90 percent of all cases.
- Papillary tumors develop more often during 30 to 60 years of age.
- They occur three times more often in women than in men.
- The cure rate is usually 97 percent or better.
- Papillary tumors often spread to lymph nodes in the neck (about 25 percent of the time), but rarely spread to distant organs.
- Distant metastases to lung, bones and other sites are rare (<3 percent at time of initial diagnosis).\
Follicular Thyroid Carcinoma (including Hurthle Cell Carcinoma)
- Follicular thyroid cancers are the second most common thyroid cancer, comprising about 15 percent of total cases.
- Follicular thyroid cancers usually develop during 40-60 years of age.
- They occur three times more often in women than men.
- The cure rate is typically 90 percent or better.
- Metastasis to the lymph nodes is less common than in papillary cancers
- Metastasis to distant organs (for example. lungs, bones, brain, or liver) is more common than with papillary carcinoma.
- Medullary thyroid cancers are a rare type of thyroid cancer and accounts for about three to five percent of all thyroid cancer cases.
- It occurs more often in older adults.
- Metastasis to the lymph nodes is common at the time of diagnosis.
- Prognosis varies depending on extent of disease at time of diagnosis and post-operative calcitonin levels.
- Anaplastic tumors are the least common type of thyroid cancer, making up only one percent of all thyroid cancer cases.
- The tumors grow rapidly, are difficult to treat and the cure rate is very low.
- The average age of onset is 65 years of age and older.
- Men are two times more likely than women to have anaplastic cancer.
- The prognosis is generally poor due to the aggressive nature of these cancers.