From the Guidelines
There are four main types of thyroid cancer: papillary, follicular, medullary, and anaplastic thyroid cancer, with papillary being the most common type, accounting for about 89.8% of all cases, as reported in the most recent study 1. The main characteristics of these types are as follows:
- Papillary thyroid cancer typically grows slowly with an excellent prognosis.
- Follicular thyroid cancer is the second most common type, making up about 4.5% of cases, and also has a good prognosis though it can spread more readily through blood vessels.
- Medullary thyroid cancer originates from C cells that produce calcitonin and accounts for about 1.6% of thyroid cancers; it can be sporadic or hereditary as part of Multiple Endocrine Neoplasia type 2 syndromes.
- Anaplastic thyroid cancer is the rarest and most aggressive form, representing less than 2% of cases, with a poor prognosis due to its rapid growth and early metastasis. Treatment approaches vary by type but generally include surgery, radioactive iodine therapy, thyroid hormone therapy, and in some cases, targeted therapy or chemotherapy, as outlined in the NCCN Guidelines for Thyroid Carcinoma 1. Some key points to consider in the management of thyroid cancer include:
- The role of molecular testing for differentiated thyroid carcinoma, as discussed in the NCCN Guidelines Insights 1.
- The implications of the new pathologic diagnosis of noninvasive follicular thyroid neoplasm with papillary-like nuclear features, as noted in the NCCN Guidelines Insights 1.
- The addition of a new targeted therapy option for BRAF V600E–mutated anaplastic thyroid carcinoma, as reported in the NCCN Guidelines Insights 1. Early detection through physical examination and ultrasound is crucial for successful treatment outcomes, especially for the more aggressive types, as emphasized in the ACR Appropriateness Criteria for thyroid disease 1.
From the Research
Types of Thyroid Cancer
- Papillary thyroid cancer: accounts for approximately 84% of all thyroid cancers 2
- Follicular thyroid cancer: accounts for approximately 4% of all thyroid cancers 2
- Oncocytic thyroid cancer: accounts for approximately 2% of all thyroid cancers 2
- Medullary thyroid cancer: accounts for approximately 4% of all thyroid cancers, arises from parafollicular C cells 2, 3, 4, 5
- Anaplastic thyroid cancer: accounts for approximately 1% of all thyroid cancers, is an aggressive form of follicular cell-derived thyroid cancer 2, 3, 5
- Poorly differentiated thyroid cancer: accounts for approximately 5% of all thyroid cancers, is an aggressive form of follicular cell-derived thyroid cancer 2
- Well-differentiated thyroid cancer: includes papillary, follicular, and oncocytic forms, arises from thyroid follicular cells 2
Rare Phenomenon of Co-existence
- Co-existence of papillary and medullary thyroid carcinoma: is a rare phenomenon, occurs in less than 1% of all thyroid tumors 4