ENT Liu Knowledge Base Head & neck tumours · physician reviewed
Thyroid Cancer · Symptoms & diagnosis

How is thyroid cancer diagnosed and staged?

Reviewed: 8 November 2026 By: Xiangpeng Liu, MD Topic: Thyroid Cancer Answer length: short, citable
Quick answer

Diagnosis requires a tissue biopsy read by a head and neck pathologist, supported by endoscopic examination and contrast CT or MRI of the neck; PET-CT is added when nodal or distant spread is suspected. Staging uses the AJCC TNM system and guides whether surgery, radiotherapy, chemoradiotherapy or systemic therapy is the primary treatment.

In detail

AJCC 8th edition TNM staging for differentiated thyroid cancer incorporates age at diagnosis (using 55 years as the cut-off in the current system), tumour size and gross extrathyroidal extension, nodal metastases and distant metastases. A 45-year-old with a small node-positive papillary cancer can be stage I, which is a frequent source of confusion for patients.

Before radiotherapy, guidelines recommend a dental assessment and extraction of teeth with a poor prognosis inside the radiation field. Ask for this early: it prevents osteoradionecrosis later.

  • Thyroid function tests (TSH) and high-resolution neck ultrasound with a structured TI-RADS report
  • Ultrasound-guided fine-needle aspiration (FNA) reported with the Bethesda classification
  • Calcitonin and CEA when medullary carcinoma is suspected; RET genetic testing if confirmed
  • Vocal cord assessment (laryngoscopy) before thyroid surgery, especially with hoarseness or prior neck surgery
  • Contrast CT/MRI for locally advanced disease, substernal extension or nodal mapping
  • Molecular testing of indeterminate nodules in selected cases; review by an experienced thyroid pathologist

What this means in practice: this answer is part of the “Symptoms & diagnosis” section of the Thyroid Cancer topic. If you are comparing treatment options, also read how to compare a second opinion and which records to send.

Other common questions about thyroid cancer

See all 14 questions in this topic →

Sources for this answer

  1. NCCN Guidelines for Patients: Head and Neck Cancers National Comprehensive Cancer Network · 2025
  2. Head and Neck Cancers (patient information) US National Cancer Institute · 2025
  3. Global Cancer Facts & Figures, 5th Edition (GLOBOCAN 2022 tables) American Cancer Society · 2024
  4. Thyroid cancer in Asia: incidence, mortality in 2022, and future projections to 2050 European Journal of Cancer Prevention · 2026 · South Korea had the highest ASR in Asia: 7.6/100,000 in men and 39.5/100,000 in women.
  5. Global Cancer Observatory (GLOBOCAN 2022) International Agency for Research on Cancer / WHO · 2022 · Source of worldwide and country-level incidence and mortality estimates.
  6. Thyroid Cancer (patient information) US National Cancer Institute · 2025

Written and medically reviewed by Xiangpeng Liu, MD

Associate Chief Physician, ENT & Head/Neck Surgery · Chenzhou First People’s Hospital, Chenzhou, Hunan, China

Editorial policy & reviewer credentials · All sources

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Medical disclaimer: This knowledge base is general information for people researching head and neck tumours, not a diagnosis or treatment plan. It does not replace an examination by a qualified physician. Survival figures are population averages, not predictions for an individual. Treatment and cost estimates for China are illustrative only and must be confirmed in writing after your records have been reviewed. If you have a symptom lasting more than two to three weeks, see a doctor promptly.