Papillary thyroid cancer (also sometimes called papillary thyroid carcinoma) is the most common type of thyroid cancer. You may have even heard your doctor talk about metastatic papillary thyroid cancer ("metastatic" means that it has spread beyond your thyroid gland). This article will focus on papillary thyroid cancer basics, including papillary thyroid cancer symptoms, treatments, and prognosis. You can read a general overview of thyroid cancer in our Introduction to Thyroid Cancer article.
Visit our Patients' Guide to Thyroid Cancer for complete information on all types of thyroid cancer, including papillary thyroid cancer.
Papillary thyroid carcinoma is the most common thyroid cancer. About 80% of all thyroid cancers cases are papillary thyroid cancer.1 What are some papillary thyroid cancer signs and symptoms? Papillary carcinoma typically arises as an irregular, solid or cystic mass that comes from otherwise normal thyroid tissue. This cancer has a high cure rate with 10-year survival rates for all patients with papillary thyroid cancer estimated at 80% to 90%. Cervical metastasis (spread to lymph nodes in the neck) are present in 50% of small papillary carcinomas and in more than 75% of the larger papillary thyroid carcinomas.
The presence of lymph node metastasis in these cervical areas causes a higher recurrence rate but not a higher mortality rate. Distant metastasis is uncommon, but lung and bone are the most common sites if the papillary carcinoma does spread. Tumors that invade or extend beyond the thyroid capsule have a much worse prognosis because of a high local recurrence rate.
But what do doctors look for to diagnose papillary thyroid cancer?
These proponents of conservative surgical therapy relate the low rate of clinical tumor recurrence (5% to 20%) despite the fact that small amounts of tumor cells can be found in up to 88% of the opposite lobe thyroid tissues. They also cite some studies showing an increased risk of and recurrent laryngeal nerve injury in patients undergoing total thyroidectomy (since it is an operation on both sides of the neck).
Proponents of total thyroidectomy (more aggressive surgery) cite several large studies that show that in experienced hands, the incidence of recurrent nerve injury and permanent hypoparathyroidism are quite low (about 2%). More importantly, these studies show that patients with total thyroidectomy followed by radioiodine therapy and thyroid suppression, have a significantly lower recurrence rate and lower mortality when tumors are greater than 1.5 cm. Remember that it is also desirable to reduce the amount of normal gland tissue that will take up radioiodine.
Based on the these studies and the above natural history and epidemiology of papillary carcinoma, the following is a typical plan for treating papillary thyroid cancer: Papillary carcinomas that are well circumscribed, isolated, and less than 1 cm in a young patient (20 to 40) without a history of radiation exposure may be treated with hemithyroidectomy and isthmusthectomy.
What are some other papillary thyroid cancer treatments? All other patients should probably be treated with total thyroidectomy and removal of any enlarged lymph nodes in the central or lateral neck areas. The surgical options are covered in greater detail (with drawings) on our article on surgical options for thyroid cancer. Often, other characteristics of the tumor that can be seen under the microscope will have an influence on whether the surgeon should take all the thyroid out (things such as vascular invasion, nerve invasion, and capsule invasion).
Thyroid cells are unique in that they have the cellular mechanism to absorb iodine. The iodine is used by thyroid cells to make thyroid hormone. No other cell in the body can absorb or concentrate iodine. Physicians can take advantage of this fact and give radioactive iodine to patients as a treatment option for papillary thyroid cancer.
There are several types of radioactive iodine, with one type being toxic to cells. Papillary thyroid cancer cells absorb iodine; therefore, they can be destroyed by giving the toxic isotope (I-131). Again, not everyone with papillary thyroid cancer needs this treatment, but those with larger tumors, tumors that have spread to lymph nodes or other areas, tumors that are aggressive microscopically, and older patients, may benefit from this treatment.
This is an extremely effective type of "chemotherapy" will little or no potential downsides (eg, no hair loss, nausea, or weight loss).
Uptake is enhanced by high thyroid-stimulating hormone (TSH) levels. To raise TSH patients can either stop taking their thyroid replacement medication or undergo 2 injections of Thyrogen® prior to undergoing radioactive iodine therapy (or radioiodine remnant ablation). In addition, patients need to be on a low iodine diet for at least 1 to 2 weeks before being treated with radiactive iodine. It is usually given 6 weeks after surgery (although it depends on the patient), and it can be repeated every 6 months if necessary (within certain dose limits).
Regardless of whether a patient has just one thyroid lobe and the isthmus removed, or the entire thyroid gland removed, most experts agree they should be placed on thyroid hormone replacement for the rest of their lives. This replaces the hormone in those who have no thyroid left, and to suppress further growth of the gland in those with some tissue left in the neck.
There is good evidence that papillary carcinoma responds to TSH secreted by the pituitary, therefore, exogenous thyroid hormone is given, which results in decreased TSH levels and a lower impetus for any remaining cancer cells to grow. Recurrence and mortality rates have been shown to be lower in patients receiving suppression.
In addition to the usual cancer follow up, patients should receive a yearly chest x-ray as well as thyroglobulin levels. Thyroglobulin is not useful as a screening for initial diagnosis of thyroid cancer, but it is quite useful in follow up of a well-differentiated carcinoma (if a total thyroidectomy has been performed). A high serum thyroglobulin level that had previously been low following total thyroidectomy, especially if gradually increased with TSH stimulation, is virtually indicative of recurrence. A value of greater than 10 ng/ml is often associated with recurrence even if an iodine scan is negative.
Papillary Thyroid Cancer Conclusion
Talk to your doctor about any questions you have about papillary thyroid cancer, including questions about symptoms, causes, and treatments.