Thyroid cancer is not a common cancer in the United States, though the number of people diagnosed with the condition is rising, according to the MayoClinic.com. Women have thyroid cancer more often than men: in 2011, an estimated 36,550 women were diagnosed with thyroid cancer, compared to 11,470 men, noted the National Cancer Institute.
Risk Factors of Thyroid Cancer
Columbia University Medical Center noted that 20 to 25 percent of patients with medullary thyroid cancer and 5 percent of patients with papillary thyroid cancer have a family member who had thyroid cancer.
One type of medullary thyroid cancer, MEN 2A associated medullary thyroid cancer, usually results from a mutation of the gene RET proto-oncogene. Another type of medullary thyroid cancer, familial medullary thyroid cancer, is passed down through families.
Another genetic condition that increases the risk of thyroid cancer is familial adenomatous polyposis, a condition in which the patient develops multiple benign polyps in her colon that will become malignant if not removed. Cetta et al. noted that papillary thyroid cancer is a rare manifestation of familial adenomatous polyposis.
Exposure to radiation is another risk factor of thyroid cancer, such as radiation therapy that is targeted to the neck. Before the link between radiation and thyroid cancer was known, radiation was used to treat many benign diseases.
MedlinePlus noted that people who had radiation therapy during childhood have an increased risk of thyroid cancer. People exposed to radiation through nuclear plant accidents or nuclear weapons also have a higher risk of developing thyroid cancer.
People who have either had a goiter or who have a family history of goiters also have an increased risk of developing thyroid cancer. A goiter is a noncancerous enlargement of the thyroid gland. Goiters may occur for unknown reasons.
People who do not get enough iodine in their diet may develop colloid goiters, or endemic goiters. MedlinePlus stated that on some occasions, medications such as aminoglutethimide and lithium can cause nontoxic goiters, or sporadic goiters.