Thyroid Cancer Overview for the Physician Assistant Exam
The Physician Assistant Exam (PANCE) will expect you to know the basics for thyroid cancer. As with thyroid disease in general, thyroid cancer affects women more often than men. The most common clinical presentation is a thyroid nodule.
Other symptoms can include hoarseness and difficulty swallowing. Ask about any prior radiation exposure, especially to the neck area. The only way to determine which type of cancer you’re dealing with is via a fine needle biopsy.
The thyroid is located in the anterior mediastinum. Differential diagnoses of anterior mediastinal masses include four t’s — thyroid masses, teratomas, terrible lymphomas, and thymomas.
Here are the types of thyroid cancer you may need to know for the PANCE:
Papillary thyroid cancer: This is the most common cause of thyroid malignancy. It accounts for about 75 percent of all thyroid cancer and is usually insidious in onset. Papillary cancer spreads via the lymph nodes. This malignancy isn’t usually considered to be very aggressive, and surgical intervention with total thyroidectomy can be done, depending on the size of the nodule.
Follicular cancer: Follicular cancer accounts for about 10 percent of thyroid malignancies. Whereas papillary cancer spreads via the lymph nodes, follicular cancer spreads via the blood (hematogenously). The treatment is surgery.
Medullary thyroid cancer (MTC): Medullary thyroid cancer is uncommon, accounting for only 2 to 5 percent of all cases of thyroid cancer. There are two points concerning medullary cancer worth mentioning:
Medullary thyroid cancer can have high levels of calcitonin, made by the parafollicular cells (C-cells).
Medullary thyroid cancer can be part of several endocrine disorders, including the multiple endocrine neoplasia (MEN) complex of syndromes. It’s associated with both MEN 2A and MEN 2B. Look for the presence of a pheochromocytoma and problems with the parathyroid (usually hyperparathyroidism).
Medullary thyroid cancer is a fairly aggressive cancer, and surgery is the treatment of choice. Calcitonin levels can be followed to monitor recurrence of disease.
Anaplastic thyroid cancer: This form of cancer is rare (less than 1 percent of all thyroid cancers) and is very, very aggressive, with a very high mortality rate: The ten-year survival rate is 14 percent. The workup includes a fine needle biopsy, thyroid function tests, calcitonin and thyroglobulin levels, and imaging for metastatic disease.
Lymphomas: Lymphomas represent only a small percentage of causes of thyroid malignancies.