A woman's risk of developing thyroid cancer is three times greater than a man's. Most people who develop thyroid cancer are 50 years of age or older, but the disease can affect teenagers and young adults. Thyroid cancers are grouped into four types, depending on how the cells look under the microscope. The types are papillary, follicular, medullary, and anaplastic thyroid cancers. The cancers grow at different rates, so the aggressiveness of each cancer is different.
Papillary cancer develops in the cells that produce thyroid hormones containing iodine.
It is a slow-growing cancer and can be treated successfully. Follicular cancers also develop in the cells that produce iodine-containing hormones. Many of the follicular cancers have a good cure rate, but if the cancer invades blood vessels or grows into nearby structures in the neck, it may be difficult to control. These cells produce a hormone called calcitonin, which does not contain iodine. These cancers are more difficult to control because they have a tendency to spread to other parts of the body.