Thyroid cancer is cancer that develops from the tissues of the thyroid
gland. It is a disease in which cells grow abnormally and have the potential
to spread to other parts of the body. Symptoms can include swelling or a lump
in the neck, difficulty swallowing or voice changes including hoarseness, or a
feeling of something being in the throat due to mass effect from the tumor.
However, most cases are asymptomatic. Cancer can also occur in the thyroid
after spread from other locations, in which case it is not classified as
thyroid cancer.
Risk factors include radiation exposure at a young age, having an enlarged
thyroid, family history and obesity.