The thyroid is an organ at the base of the throat that makes hormones that
help control heart rate, blood pressure, body temperature, and weight.
Four main types of thyroid cancer are papillary, follicular, medullary,
and anaplastic thyroid cancer. The four types are based on how the cancer
cells look under a microscope.
Papillary and follicular thyroid cancers account for 80-90% of all thyroid
cancers. Both types begin in the follicular cells of the thyroid. Most
of this type tends to grow slowly and if detected early, most can be treated
successfully.
Medullary thyroid cancer accounts for 5-10% of thyroid cancer cases and
it arises in C cells not follicular cells. Medullary thyroid cancer is
easier to control if it is found and treated before it spreads to other
parts of the body. Anaplastic cancer is least common with only 1-2% of
cases. It arises in follicular cells and the cells are highly abnormal
and difficult to recognize. This type of cancer is usually very hard to
control because the cancer cells tend to grow and spread very quickly.
The exact cause of thyroid cancer is unknown however; certain risk factors
are more likely to contribute to thyroid cancer in one individual versus
another. The risk factors associated with an increased chance of developing
thyroid cancer are radiation, family history, being female, age, race,
and not enough iodine in the diet. Early thyroid cancer does not cause
symptoms. As cancer grows symptoms may include a lump or nodule in the
front of the neck near the Adam’s apple, hoarseness or difficulty
speaking in a normal voice, swollen lymph nodes, especially in the neck,
difficulty swallowing or breathing or pain in the throat or neck. If a
person has symptoms that suggest thyroid cancer the doctor may perform
a physical exam and ask about the patient’s personal and family
medical history. Lab tests and imaging including ultrasound, radionuclide
scanning, and a biopsy may also be performed. A biopsy is the removal
of tissue to look for cancer cells and is the only sure way to know whether
a nodule is cancerous. The tissue is examined under a microscope by a
pathologist for diagnosis.
If the diagnosis is thyroid cancer, the doctor then needs to know the extent
or stage of the disease. Additional testing including ultrasound, MRI,
CT scan, and radiounuclide scan may be done to see whether the cancer
has spread to the lymph nodes or other areas within the neck. After testing
and staging are complete treatment options are discussed. Treatment options
are surgery, radioactive iodine therapy, hormone treatment, external radiation
therapy, and chemotherapy.
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