Thyroid Cancer

What it is

Overview

Thyroid cancer is the most common endocrine malignancy. It encompasses several distinct types — papillary (most common, ~85%), follicular, medullary, and anaplastic (least common but most lethal). Incidence has risen dramatically over the past decades, largely due to increased detection of small nodules through neck ultrasound. Most thyroid cancers have excellent prognoses; anaplastic thyroid cancer is one of the most lethal cancers known.

Biology

How It Develops

Papillary thyroid cancer is driven by BRAF V600E mutation (~45%) or RET/PTC rearrangements. These activate the MAPK signaling pathway. Medullary thyroid cancer arises from C-cells (parafollicular cells) and is associated with RET proto-oncogene mutations — germline in MEN2 syndrome. Anaplastic thyroid cancer evolves from dedifferentiated papillary or follicular cancer with catastrophic genomic instability.

Warning signs

Symptoms

• —Lump or nodule in the neck (most common presentation)
• —Hoarseness or voice changes
• —Difficulty swallowing
• —Neck pain or pressure
• —Swollen lymph nodes in the neck
• —Anaplastic: rapidly growing neck mass with airway compromise

Detection

Diagnosis Methods

• —Neck ultrasound
• —Fine-needle aspiration (FNA) biopsy
• —Thyroid function tests
• —CT or MRI for locally advanced disease
• —Thyroglobulin (tumor marker for differentiated thyroid cancer)
• —Calcitonin (for medullary thyroid cancer)
• —Genetic testing (RET, BRAF, RAS)

Medical care

Treatment Options

• —Surgery (thyroidectomy with or without neck dissection)
• —Radioactive iodine (RAI/I-131) ablation for differentiated cancer
• —TSH suppression therapy (levothyroxine)
• —External beam radiation (for invasive or unresectable disease)
• —Targeted therapy (lenvatinib, sorafenib for RAI-refractory; vandetanib, cabozantinib for medullary)
• —BRAF/MEK inhibitors + pembrolizumab for anaplastic thyroid cancer

Data

Statistics

Prevention

Risk Factors

• —Radiation exposure to the neck or head (especially in childhood)
• —Family history of thyroid cancer
• —MEN2 syndrome (medullary thyroid cancer)
• —Female sex (3x higher risk)
• —Age 25–65

Further reading

Resources