Thyroid Tumor Staging
Defining the size and characteristics of a cancerous thyroid tumor
After thyroid cancer is diagnosed, it is staged. Staging is a tool your doctor uses to classify characteristics about your malignant thyroid tumor. Staging the tumor helps your doctor determine the best treatment for your thyroid cancer. The staging system was developed by the American Joint Committee on Cancer (AJCC) and is called the TNM System. The letter T stands for tumor, N for nodes and M means metastasis.
One or more of the following may help stage your thyroid cancer:
- Ultrasound examination
- Pathology: biopsy obtained before or during surgery
- Imaging: CT scan and/or MRI (magnetic resonance imaging)
- Nuclear imaging: Full body scan may be performed using CT scan or PET scan (Positron Emission Tomography) and involves an intravenous injection of a radioactive substance. Thyroid cancer cells 'take up' the radioactive tracer and can show if and where cancer has spread in other parts of your body.
TNM System Basics
- T = Size of the main tumor (there may be more than one tumor)
- N = Degree of spread to the local lymph nodes
- M = Indicates if the tumor has spread (metastasized) beyond the neck (eg, lungs)
"T" Thyroid Cancer Categories
- TX = Tumor cannot be evaluated
- T0 = There is no primary tumor
- T1 = Tumor size is 2 cm wide or smaller
- T2 = Tumor size is 2-4 cm wide
- T3 = Tumor size is greater than 4 cm or has started to grow outside the thyroid
- T4a = The tumor (any size) has grown extensively beyond the thyroid gland into local neck tissues
- T4b = Tumor has grown back toward the spine or into local large blood vessels
"N" Thyroid Cancer Categories
- NX = Local lymph nodes cannot be evaluated
- N0 = No spread to local lymph nodes
- N1 = Tumor has spread to local lymph nodes
- N1a = Tumor has spread to lymph nodes around the thyroid
- N1b = Tumor has spread to lymph nodes in the sides of the neck or upper chest
"M" Thyroid Cancer Categories
- MX = Distant metastasis (ie, spread) cannot be evaluated
- M0 = No distant metastasis
- M1 = Distant metastasis involves distant lymph nodes, internal organs, etcetera
Bridget Brady, MD, FACS is the first fellowship-trained endocrine surgeon in Austin, Texas. She has a passion for and expertise in disease of the thyroid, parathyroid, and adrenal glands. Dr. Brady has performed thousands of thyroidectomies and parathryoidectomies with a focus on minimally invasive techniques to optimize patients’ medical and cosmetic outcomes.
AJCC. American Joint Committee on Cancer. https://cancerstaging.org/references-tools/Pages/What-is-Cancer-Staging.aspx. Accessed June 21, 2016.
ThyCa: Thyroid Cancer Survivors' Association. Thyroid Cancer Types, Stages and Treatment Overview. Last Updated June 2, 2016. http://www.thyca.org/about/types/#u45. Accessed June 21, 2016.