Diagnosis
If a person has any symptoms of thyroid cancer, a doctor should conduct a physical examination and take their full medical history. During the physical exam, the doctor should thoroughly examine the neck and throat for any lumps or swelling. If the doctor suspects thyroid cancer, he or she may recommend any of the following procedures to diagnose and stage the disease.
Ultrasound
Ultrasounds bounce sound waves off of your internal organs in order to create echoes that form a picture. An ultrasound can show how big the thyroid tumor is, and whether it is solid or filled with fluid. Solid tumors are more likely to be malignant than fluid-filled tumors. The doctor may also use an ultrasound to check the number and size of nodules on the thyroid, and to check for any enlarged lymph nodes that could mean cancer spread outside the thyroid.
Needle Aspiration
A biopsy obtained by a very small needle (aspiration) is the best way to assess if thyroid cancer is present. The doctor will usually first order blood tests and an ultrasound to get a better idea of whether you have thyroid cancer. Usually the aspiration will be performed with ultrasound guidance. The doctor will then obtain a tissue sample from a thyroid nodule using a thin needle. The doctor may repeat this procedure multiple times, taking samples from different parts of the thyroid nodules or from any suspicious looking lymph nodes found in the neck near the thyroid. The doctor will then send these samples to a laboratory to be examined under a microscope. If the samples do not provide a definite diagnosis, the doctor may rarely need to perform a core needle biopsy or a surgical biopsy and take a larger tissue sample. Occasionally, genetic testing can be done on the aspirated material to better assess the risk of cancer when the pathology reading carries mild to moderate risk for cancer.
Blood Tests
The doctor may recommend blood tests to measure the levels of certain hormones in your blood, such as TSH, to ensure that your thyroid is functioning properly. Tests may also be ordered for calcitonin and CEA if there is reason to suspect medullary thyroid carcinoma. Abnormal levels of calcitonin and CEA hormones may indicate the possibility of cancer, so, in general, these tests can help your doctor determine if your thyroid is working properly.
Radioactive Scan
Doctors may use this test after a surgery for papillary or follicular thyroid cancer to see if it has spread to other parts of the body, or to see if there is need for treatment with a larger amount of radioactive iodine. These forms of thyroid cancer usually absorb iodine. The patient takes an oral dose of radioactive iodine, which gets absorbed by the thyroid cancer cells, and helps identify tumors on imaging tests.
Computed tomography (CT) scan
A computed tomography (CT) scan uses X-rays to produce an image of your body. A special dye may be injected into your veins and you may be asked to drink a special fluid in order to make the internal organs stand out. A CT scan reveals the presence of tumors and whether or not the cancer has spread to other parts of the body. However, occasionally doctors prefer MRIs to CT scans for thyroid cancer, because CT scans use a contrast dye that contains iodine. This can interfere with radioiodine scans. However, if a CT scan is optimal to evaluate the neck, your doctor may decide that the contrast is worth administering.
Magnetic resonance imaging (MRI) scan
Magnetic resonance imaging (MRI) uses a powerful magnet to produce detailed images of body parts. Magnetic waves are absorbed by the body and then released in a certain pattern, which is translated by a computer in order to show "slices" of the body. MRI scans produce detailed images of the soft-tissues and can help spot areas where cancer has spread.
Positron emission tomography (PET) scan
For a PET scan, the doctor injects a radioactive substance into the patient's bloodstream. This substance collects in malignant (cancerous) cells in the patient's body. The doctor then uses a PET scanner to detect these areas of radioactivity and to find the exact location of cancer in the patient's body. PET scans are most useful for anaplastic carcinoma and certain forms of papillary and follicular carcinomas that do not concentrate radioiodine well. However, PET scans are often less needed in evaluating medullary carcinoma.
Laryngoscopy
The doctor uses a laryngoscope (narrow, flexible tube with a camera and light on the end) to examine the vocal chords. Surgery for thyroid cancer occasionally affects nerves that control the vocal chords, so the doctor may recommend this test to make sure the vocal chords are functioning properly before and after surgery.
