Doctors use many tests to find, or diagnose, cancer. They also do tests to learn if cancer has spread to another part of the body from where it started. A biopsy is the only certain way to confirm a diagnosis of cancer. When performing a biopsy, the doctor takes a sample of tissue for testing in a laboratory. The sample may be removed using a needle and or may be removed during the surgery to treat the nodule. If initial tests indicate that the nodule is cancerous, a surgery will be scheduled to remove as much of the cancer as possible and to determine the extent of spread or the stage of the cancer.1
Fine needle aspiration: Fine needle aspiration is a technique that uses a needle and syringe to withdraw a sample of the cells from a thyroid nodule. The cells can then be evaluated under a microscope to determine if they are cancerous or benign. Since many thyroid nodules are benign, this technique provides a minimally invasive way to determine if surgery is necessary.
When diagnosed with cancer further tests are necessary to determine the extent of spread (stage) of the cancer. Cancer’s stage is a key factor in determining the best treatment. The stage of cancer may be determined at the time of diagnosis or it may be necessary to perform additional tests. In addition to a through history and physical exam, tests used to diagnose, and stage thyroid cancer may include the following:
Ultrasound: Ultrasound uses high frequency sound waves and their echoes to create a two-dimensional image that is projected on a screen. Ultrasound is a simple procedure that may allow doctors to determine if a thyroid nodule is cancerous or benign based on the appearance of the image that is produced. A limitation of ultrasound is that it does not produce a sample of the cells that can be evaluated under a microscope.
About half the people diagnosed with papillary thyroid cancer have lymph node metastases. Neck mapping by ultrasound can be used to evaluate the lymph nodes in the neck for metastatic disease from the jaw down to the clavicle. This is important to ensure that the initial surgery is appropriate for the stage.2, 3
Positron emission tomography (PET): Positron emission tomography scanning is an advanced technique for imaging body tissues and organs. One characteristic of living tissue is the metabolism of sugar. Prior to a PET scan, a substance containing a type of sugar attached to a radioactive isotope (a molecule that emits radiation) is injected into the patient’s vein. The cancer cells “take up” the sugar and attached isotope, which emits positively charged, low energy radiation (positrons) that create the production of gamma rays that can be detected by the PET machine to produce a picture. If no gamma rays are detected in the scanned area, it is unlikely that the mass in question contains living cancer cells.
Computed Tomography (CT) Scan: A CT scan is a technique for imaging body tissues and organs, during which X-ray transmissions are converted to detailed images, using a computer to synthesize X-ray data. A CT scan is conducted with a large machine positioned outside the body that can rotate to capture detailed images of the organs and tissues inside the body.1
Thyroid Blood Tests:
TSH (thyroid-stimulating hormone) is recommended when a thyroid nodule is present. This hormone is made by the pituitary to regulate the thyroid. TSH tells the thyroid to make hormones that control things like your metabolism. In general, when the TSH is high it usually means that the thyroid levels are low. Likewise, when the TSH is low, it usually means that the thyroid levels are high.
Thyroglobulin is a protein made by the thyroid that can be measured after treatment (surgery) and during follow-up care. If the protein is present, there may still be cancer cells in the body. If it becomes elevated, this could be a sign that the cancer is coming back, and more treatment is needed.
Calcitonin: The C cells in the thyroid make calcitonin. Medullary thyroid cancer starts in the C cells. If you are at risk for medullary thyroid cancer, you may have your calcitonin level checked. It can also be measured after treatment for medullary thyroid cancer. Calcitonin may affect how calcium is made in the body.
Precision Medicine & Personalized Cancer Care
Not all thyroid cancer cells are alike. They may differ from one another based on what genes have mutations that are responsible for the growth of the cancer. Testing is performed to identify genetic mutations or the proteins they produce that drive the growth of the cancer. Once a genetic abnormality is identified, a specific targeted therapy can be designed to attack a specific mutation or other cancer-related change in the DNA programming of the cancer cells. Precision cancer medicine uses targeted drugs and immunotherapies engineered to directly attack the cancer cells with specific abnormalities, leaving normal cells largely unharmed.
Researchers are identifying cancer driving genetic mutations responsible for thyroid cancer on an ongoing basis. The following mutations are known to exist in thyroid cancer and precision cancer medicines are either available for use or being developed in clinical trials. Patients should discuss the role of genomic-biomarker testing for the management of their cancer with their treating oncologist.
BRAF: Genetic mutation occurs in ~ 40% of papillary thyroid cancer patients.
MEK: Occurs commonly with BRAF.
RAS Genes: KRAS and NRAS: RAS is estimated to be present in 20% of papillary and 40% of follicular thyroid cancers.
RET: Occurs in ~ 15% of papillary and can occur in medullary thyroid cancer.
PIKC3A: Occurs in 42% of anaplastic and 24% of follicular thyroid cancers.
PTEN Occurs in~ 12% of anaplastic thyroid cancers.
PAX8-PPAR occurs in ~35% of follicular thyroid cancers.
Stages of Thyroid Cancer
Stage I-II: Stage I-II thyroid cancers are generally confined to the thyroid but may include multiple sites of cancer within the thyroid. Thyroid cancer that has spread to nearby lymph nodes is still considered to be in stage I-II when the patient is younger than 45 years of age as the presence of cancer in the lymph nodes does not worsen the prognosis for these younger patients.
Stage III: Stage III thyroid cancer is greater than 4 cm in diameter and is limited to the thyroid or may have minimal spread outside the thyroid. Lymph nodes near the trachea may be affected. Stage III thyroid cancer that has spread to adjacent cervical (neck) tissue or nearby blood vessels has a worse prognosis than cancer confined to the thyroid. However, lymph node metastases do not worsen the prognosis for patients younger than 45 years. Stage III thyroid cancer is also referred to as locally advanced disease.
Stage IV: Stage IV thyroid cancer has spread beyond the thyroid to the soft tissues of the neck, lymph nodes in the neck, or distant locations in the body. The lungs and bone are the most frequent sites of distant spread. Papillary carcinoma more frequently spreads to regional lymph nodes than to distant sites. Follicular carcinoma is more likely to invade blood vessels and spread to distant locations.
Recurrent: Thyroid cancer that has recurred after treatment or progressed with treatment is called recurrent disease.
1 American Cancer Society: Cancer Facts and Figures 2017. Atlanta, Ga: American Cancer Society, 2017.
2 Adam MA, Pura J, Goffredo P, et al. Presence and number of lymph node metastases are associated with compromised survival for patients younger than age 45 years with papillary thyroid cancer. Journal of Clinical Oncology. 2015;33(21):2370-75. doi: 10.1200/JCO.2014.59.8391.
3 Robinson TJ, Thomas S, Dinan MA, Roman S, Sosa JA, Hyslop T. How many lymph nodes are enough? Assessing the adequacy of lymph node yield for papillary thyroid cancer. Journal of Clinical Oncology. 2016;34(28):3434-39. doi: 10.1200/JCO.2016.67.6437.