The thyroid gland can develop several problems, some of which are extremely common. Often, these problems can concern the production of hormone, too much or too little. Sometimes, the unusually increased growth of the thyroid can cause compression of important neck structures. People have also developed nodules or lumps within the thyroid which are worrisome for the presence of thyroid cancer. I've personally dealt with all of these thyroid problems, so I can describe them in some detail, but I want to focus on Medullary Thyroid Cancer on this page.
Many thyroid cancers are curable.
The most common types of thyroid cancer, papillary and follicular are the most curable. Medullary cancer of the thyroid is significantly less common, and it has a worse prognosis. Medullary cancers tend to spread to large numbers of lymph nodes very early on, and therefore it requires a much more aggressive operation than does the more localized cancers such as papillary and follicular. This cancer requires complete thyroid removal and a dissection to remove the lymph nodes of the front and sides of the neck. If this cancer is found after it has already spread, it cannot be cured in most cases.