University of Virginia Health System

Thyroid cancer in the United States represents a small but significant number of patients in most referral centers. New cases of thyroid cancer may occur in 15,000 to 20,000 patients annually in the United States. The primary treatment for thyroid cancer is surgical. There are four types of cancer. The most common is papillary carcinoma of the thyroid (70 -75% of cases). The second most common is follicular carcinoma (10 - 15% of cases). Together, these two are often referred to in the literature as "well-differentiated" thyroid cancers. With appropriate surgical treatment the prognosis for patients with well-differentiated thyroid cancer is excellent. Younger patients may have a higher rate of local lymph node involvement. This sometimes involves more extensive surgery including total thyroidectomy and local lymph node resection. This has not been found to change long term survival rates.

Papillary carcinoma can be diagnosed preoperatively by ultrasound and fine needle aspiration. A patient with papillary carcinoma who has a mass less than 1.5 centimeters in one lobe of the thyroid can be treated with the removal of the lobe and the middle part of the thyroid (the isthmus). Patients who have a mass larger that 1.5 centimeters or who are older at presentation (especially males over 50) would most likely benefit from a total thyroidectomy. The referring endocrinologist may make an additional recommendation for postoperative radioiodine ablation with I-131. This can often be done as an outpatient.

Papillary cancer is often thought to be "multicentric", that is, occurring simultaneously in several regions of the thyroid at the time of diagnosis. For this reason, a recommendation for a total thyroidectomy may occur at the time of diagnosis. Research continues to look at this issue, especially in low risk patients of younger age with smaller dominant masses.

Follicular cancer is the second most common form of thyroid cancer. It arises from the follicular cells of the thyroid and may be associated with benign masses such as goiters. Follicular cancer is hard to diagnose pre-operatively, as there are no cellular characteristics that lend themselves to diagnosis by FNA (as occurs with papillary cancer). The diagnosis of follicular cancer requires a complete and throuugh evaluation of the surgically removed specimen, therefore, the diagnosis may not be made for three to five days after surgery by the pathologists. The experience of the operating endocrine surgeon is paramount. The surgeon must use his or her best judgement as to the extent of resection necessary for a "follicular" lesion.

The minimal surgical resection required for a one to two centimeter follicular cancer should be the removal of a lobe and isthmus of the thyroid. For lesions bigger then two centimeters, a total thyroidectomy plus post-operative I-131 therapy is the usual recommended therapy. Older males may have more aggressive disease, therefore should require at least total thyroidectomy.

Medullary carcinoma of the thyroid can present either as a non-familial circumstance, or as part of an inherited family syndrome known as multiple endocrine neoplasia (MEN I or II). MEN I syndrome involves patients with a combination of findings including a pituitary mass, hyperparathyroidism and a pancreatic mass. MEN II syndrome presents in families with adrenal masses (usually pheochromocytomas) parathyroid disease and medullary carcinoma of the thyroid. A patient who has a preoperative diagnosis or suggestion of medullary carcinoma of the thyroid may require additional preoperative evaluation for any of the familial disorders. Specifically, a workup for pheochromocytoma should be included. An undiagnosed pheochromocytoma can result in serious anesthetic complications if not evaluated and treated preoperatively.

Medullary carcinoma carries a poorer prognosis than the well-differentiated carcinomas. Some reports suggest that there is a 50% 5-year mortality in patients with diagnosed medullary carcinoma. The recognized surgical therapy for medullary carcinoma is total thyroidectomy and "a central lymph node" dissection. This incorporates removing all lymph nodes in the anterior part of the neck to evaluate possible metastatic spread.

Anaplastic carcinoma of the thyroid is an extremely serious and aggressive thyroid cancer which often results in the death of the patient by local recurrence and metastatic spread within several months of diagnosis. This is usually seen in older patients who have the rapid onset of a thyroid mass, pain and hoarseness. Thyroidectomy is not often helpful in stopping the rapid progression of such thyroid cancer and a tracheostomy may be in order to aid breathing. Anaplastic thyroid cancer is extremely rare involving less than 1% of patients with thyroid masses.