Although thyroid cancer is the most common cancer among endocrine cancers, it is a rare cancer compared to all cancers. Thyroid cancer is usually very treatable and is usually treated with surgery and, if necessary, radioactive iodine. Thyroid cancers, especially the more common differentiated (papillary and follicular) thyroid cancers, can be effectively treated even in advanced stages. Although the term “cancer” may be frightening, the prognosis for most patients with papillary and follicular thyroid cancer is generally excellent.
Papillary, follicular and Hürthle cell cancers that develop from follicular cells constitute 90-95% of thyroid cancers. These are classified as well-differentiated thyroid cancers. Hürthle cell cancers are considered a subgroup of follicular cancers.
Medullary cancers account for about 2% of thyroid cancers, while anaplastic cancers, a cancer with a poor prognosis, account for less than 2%. Anaplastic cancers mainly develop in iodine-deficient areas. Apart from these, lymphoma and metastatic cancers can also be seen.
Papillary thyroid cancer.
Papillary thyroid cancer is the most common type and accounts for approximately 70-80% of all thyroid cancers. Papillary thyroid cancer can occur at any age. It is 2 times more common in women than men. It tends to grow slowly and often spreads to lymph nodes in the neck. However, unlike many other cancers, it has a very good prognosis even if it has spread to the lymph nodes, especially in female patients younger than 40 years of age, the prognosis is even better. It can be more aggressive in older ages.
Follicular thyroid cancer.
Follicular thyroid cancer, one of the differentiated thyroid cancers, constitutes approximately 10% to 15% of all thyroid cancers. Follicular cancer is a disease of advanced age, which is usually seen at the age of 50 and above. It is more common in women, the female/male ratio is 3/1. Follicular cancer can spread to lymph nodes in the neck, but this is rarer than papillary cancers. On the other hand, the probability of spreading to distant organs, especially lungs and bones, is higher than papillary cancers.
The subtype of follicular cancer that develops from oxyphilic cells is known as Hürthle cell cancers and tends to occur in older people (60-75 years).
Medullary thyroid cancer.
Medullary thyroid cancer (MTC) accounts for approximately 2% of all thyroid cancers. MTKs arise from C cells or parafollicular cells of the thyroid. Approximately 25% of all MTCs are familial and may be associated with other endocrine tumors. All familial medullary cancers have mutations in the RET proto-oncogene.
Anaplastic thyroid cancer.
Anaplastic thyroid cancer is the worst course of thyroid cancers and the least likely to respond to treatment. Fortunately, it is very rare and is found in less than 2% of patients with thyroid cancer. It is more common in women, the majority of patients are in their 70s and 80s. It is rare before the age of 50. Most cases develop as a result of transformation of differentiated carcinomas.