Diagnosis

If you have symptoms that suggest thyroid cancer, your doctor will help you find out whether they are from cancer or some other cause. Your doctor will ask you about your personal and family medical history. You may have one or more of the following tests:

• Physical exam: Your doctor feels your thyroid for lumps (nodules). Your doctor also checks your neck and nearby lymph nodes for growths or swelling.
• Blood tests: Your doctor may check for abnormal levels of thyroid-stimulating hormone (TSH) in the blood. Too much or too little TSH means the thyroid is not working well. If your doctor thinks you may have medullary thyroid cancer, you may be checked for a high level of calcitonin and have other blood tests.
• Ultrasound: An ultrasound device uses sound waves that people cannot hear. The device aims sound waves at the thyroid, and a computer creates a picture of the waves that bounce off the thyroid. The picture can show thyroid nodules that are too small to be felt. The doctor uses the picture to learn the size and shape of each nodule and whether the nodules are solid or filled with fluid. Nodules that are filled with fluid are usually not cancer. Nodules that are solid may be cancer.
• Thyroid scan: Your doctor may order a scan of your thyroid. You swallow a small amount of a radioactive substance, and it travels through the bloodstream. Thyroid cells that absorb the radioactive substance can be seen on a scan. Nodules that take up more of the substance than the thyroid tissue around them are called "hot" nodules. Hot nodules are usually not cancer. Nodules that take up less substance than the thyroid tissue around them are called "cold" nodules. Cold nodules may be cancer.
• Biopsy: A biopsy is the only sure way to diagnose thyroid cancer. A pathologist checks a sample of tissue for cancer cells with a microscope.

  Your doctor may take tissue for a biopsy in one of two ways:

• Fine-needle aspiration: Most people have this type of biopsy. Your doctor removes a sample of tissue from a thyroid nodule with a thin needle. An ultrasound device can help your doctor see where to place the needle.
• Surgical biopsy: If a diagnosis cannot be made from fine-needle aspiration, a surgeon removes the whole nodule during an operation. If the doctor suspects follicular thyroid cancer, surgical biopsy may be needed for diagnosis.
  

  You may want to ask your doctor these questions before having a biopsy: Will I have to go to the hospital for the biopsy? How long will it take? Will I be awake? Will it hurt? Are there any risks? What are the chances of infection or bleeding after the biopsy? How long will it take me to recover? Will I have a scar on my neck? How soon will I know the results? Who will explain the results to me? If I do have cancer, who will talk to me about the next steps? When?

To plan the best treatment, your doctor needs to learn the extent (stage) of the disease. Staging is a careful attempt to find out the size of the nodule, whether the cancer has spread, and if so, to what parts of the body.

Thyroid cancer spreads most often to the lymph nodes, lungs, and bones. When cancer spreads from its original place to another part of the body, the new tumor has the same kind of cancer cells and the same name as the original cancer. For example, if thyroid cancer spreads to the lungs, the cancer cells in the lungs are actually thyroid cancer cells. The disease is metastatic thyroid cancer, not lung cancer. For that reason, it's treated as thyroid cancer, not lung cancer. Doctors call the new tumor "distant" or metastatic disease.

Staging may involve one or more of these tests:

• Ultrasound: An ultrasound exam of your neck may show whether cancer has spread to lymph nodes or other tissues near your thyroid.
• CT scan: An x-ray machine linked to a computer takes a series of detailed pictures of areas inside your body. A CT scan may show whether cancer has spread to lymph nodes, other areas in your neck, or your chest.
• MRI: MRI uses a powerful magnet linked to a computer. It makes detailed pictures of tissue. Your doctor can view these pictures on a screen or print them on film. MRI may show whether cancer has spread to lymph nodes or other areas.
• Chest x-ray: X-rays of your chest may show whether cancer has spread to the lungs.
• Whole body scan: You may have a whole body scan to see if cancer has spread from the thyroid to other parts of the body. You get a small amount of a radioactive substance. The substance travels through the bloodstream. Thyroid cancer cells in other organs or the bones take up the substance. Thyroid cancer that has spread may show up on a whole body scan.