Thyroid Cancer Diagnosis
Tests and Exams to Diagnose Thyroid Cancer
Unlike other cancers which are usually treated by an oncologist (doctor who specializes in diagnosing and treating cancer), thyroid cancer is usually treated by an endocrinologist (specializes in endocrine gland problems) and a surgeon. Remember that early detection and treatment are essential to a good outcome. Your doctor (ie, primary care physician) can help coordinate your care with cancer specialists.
To diagnose thyroid cancer, the doctor takes your complete medical history, reviews possible factors, other health problems, performs a physical examination, and orders tests such as blood work.
During the physical exam, the doctor palpates (feels) your neck, which may require you to swallow and flex and bend your neck. He or she will pay particular attention to the thyroid gland and surrounding tissues, such as the lymph nodes. The number, size, shape, and firmness of the nodule(s) are carefully examined. The doctor correlates the physical findings with your medical history and reported symptoms, such as pain or hoarseness.
Fact: The American Thyroid Association reports that while thyroid lumps (nodules) are common, fewer than 1 in 10 is cancer. 1
Laboratory Tests to Diagnose Thyroid Cancer
Blood is drawn to test your thyroid gland function. Results from a thyroid-stimulating hormone (TSH) test either confirms or rules out hypothyroidism (too low) or hyperthyroidism (too high) levels. If your thyroid gland does not function normally, a T3 or Free T3 (triiodothyronine) and T4 (thyroxine) test is run to determine your thyroid hormone activity levels. It is important to remember that thyroid function tests are not indicators of thyroid cancer and most people with thyroid cancer have normal thyroid function.
Family History as Part of Thyroid Cancer Diagnosis
If you have a family history of medullary thyroid cancer, the doctor will test your blood calcitonin and calcium levels. Calcitonin is a hormone important to calcium and phosphorus metabolism and bone growth. An elevated calcitonin level can indicate cancer.
A thyroid scan, or nuclear medicine scan, tests the gland's function. After a radioactive tracer (dye—iodine or technetium) is injected, a special camera captures images of the thyroid gland and measures the amount of dye the gland (nodules) absorbs.
Normal and abnormal test results are reported as functioning (normal), cold (underactive), or hot (overactive). Suspicious cold nodules can be further evaluated by a procedure called fine needle aspiration (needle biopsy). Hot nodules do not generally require biopsy.
Fine Needle Aspiration (FNA)
Depending on the size of the nodule, your doctor may perform fine needle aspiration in his office. An anesthetic numbs the area, although is usually not painful. Small tumors (less than half an inch) may require biopsy using ultrasound to guide needle placement. Fine needle aspiration usually involves taking several samples that are microscopically examined by a pathologist.
Sometimes fine needle aspiration results are not conclusive. If the doctor has reason to think the nodule may be cancerous, he or she may recommend a biopsy using a larger needle, open biopsy, or removal of one side of the thyroid gland (lobectomy). These procedures are performed under general anesthesia (sedation) in an operating room.
Results from imaging studies may assist your doctor in confirming your thyroid cancer diagnosis. Different types of imaging studies include x-ray, computed tomography (CT scan), magnetic resonance imaging (MRI), and positron emission tomography (PET scan).
Depending on your tumor's characteristics, and the close proximity of your thyroid gland to your voice box (larynx), your doctor may recommend laryngoscopy. A laryngoscope is a lighted and flexible tube with magnification used to examine your larynx.
After your doctor has evaluated each piece of information about your health, including test results, he makes his diagnosis and outlines a treatment plan for your thyroid cancer.