From the Guidelines
Thyroid carcinomas should be differentiated into four main types: papillary, follicular, medullary, and anaplastic, with treatment and management approaches tailored to each type, prioritizing morbidity, mortality, and quality of life as the primary outcomes. When differentiating thyroid carcinomas, it is essential to consider the distinct characteristics of each type, including papillary, follicular, medullary, and anaplastic carcinomas.
- Papillary thyroid carcinoma is the most common type, accounting for 80-85% of cases, and is characterized by indolent growth and excellent prognosis 1.
- Follicular thyroid carcinoma accounts for 10-15% of cases and is distinguished by capsular and vascular invasion rather than nuclear features 1.
- Medullary thyroid carcinoma arises from parafollicular C cells, produces calcitonin, and may occur sporadically or as part of hereditary syndromes like MEN2 1.
- Anaplastic thyroid carcinoma is rare but highly aggressive with poor prognosis, typically affecting older patients with rapidly growing neck masses 1.
Diagnosis of thyroid carcinomas involves a combination of fine needle aspiration cytology, imaging (ultrasound, CT, MRI), and molecular testing 1.
- The results of fine needle aspiration cytology (FNAC) are very sensitive for the differential diagnosis of benign and malignant nodules, although there are limitations, such as inadequate samples and follicular neoplasia 1.
- Measurement of serum calcitonin is a reliable tool for the diagnosis of medullary thyroid cancer, with higher sensitivity compared to FNAC 1.
Treatment of thyroid carcinomas varies by type, but generally includes surgical resection, with radioactive iodine therapy for papillary and follicular types, while medullary and anaplastic types require more aggressive approaches, including total thyroidectomy, neck dissection, and adjuvant therapy 1.
- The initial treatment of differentiated thyroid carcinoma (DTC) should always be preceded by careful exploration of the neck by ultrasound to assess the status of lymph node chains, and total or near-total thyroidectomy is recommended for most cases 1.
- Radioiodine ablation is recommended for all patients except those at very low risk, and the use of recombinant human TSH (rhTSH) is approved as preparation for radioiodine ablation 1.
Prognosis of thyroid carcinomas correlates with the degree of differentiation, with well-differentiated types having excellent survival rates compared to the dismal outcomes of anaplastic carcinoma 1.
- The 10-year survival rate for papillary carcinoma is 99%, and 95% for follicular type 1.
- The 10-year survival rate for medullary thyroid carcinoma is 82%, and 8% for anaplastic carcinoma 1.
From the Research
Types of Thyroid Carcinomas
- 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 2
- Poorly differentiated thyroid cancer accounts for approximately 5% of all thyroid cancers 2
- Anaplastic thyroid cancer accounts for approximately 1% of all thyroid cancers 2
Diagnosis and Treatment
- Fine-needle aspiration biopsy is the most common method for preoperative diagnosis of thyroid carcinomas 3
- Ultrasound evaluation is recommended before surgical resection 4
- Surgical resection is the preferred approach for patients with recurrent locoregional disease 2
- Radioactive iodine treatment after surgery improves overall survival in patients at high risk of recurrence 2
- Antiangiogenic multikinase inhibitors and targeted therapies to genetic mutations that give rise to thyroid cancer are increasingly used in the treatment of metastatic disease 2
Risk Stratification and Management
- Risk stratification systems are designed to assist in personalized management of differentiated thyroid cancer 5
- The management of differentiated thyroid cancer underwent a paradigm shift toward the use of risk stratification with the goal of maximizing the benefit and minimizing the morbidity of radioiodine therapy 6
- 131I therapy is guided by information derived from surgical histopathology, molecular markers, postoperative diagnostic radioiodine scintigraphy, and thyroglobulin levels 6