What should be done when a thyroid mass is discovered?

Thyroid nodules are common and increase in incidence with increasing age. In the U.S. more than 50 % of patients over the age of 50 have been found to have thyroid nodules. Most thyroid nodules (+/- 95%) are benign. While thyroid cancer is uncommon (+/-1% of human cancer in the U.S.) it is the most rapidly increasing cancer affecting females. The incidence of thyroid cancer in females is three times that of males.

Who is at greater risk of thyroid cancer?

Those patients who have received radiation exposure, either from external radiation (x-ray therapy) to the neck and upper chest or from radiation emitted from radioactive isotopes, e.g., the Chernobyl accident, are at increased risk of thyroid cancer. A family history of thyroid cancer - a genetic inheritance – also increases the risk of the patient having thyroid cancer, particularly of the medullary variety. Any patient presenting with a newly discovered nodule or lump in the thyroid gland should be appropriately investigated for possible cancer. Children and the elderly are at higher risk of that nodule being malignant. The sudden and unexplained onset of hoarseness or difficulty in swallowing, or the appearance of a mass in the neck may herald the diagnosis of thyroid cancer. Increasing use of diagnostic imaging studies, e.g., CT and MRI scans and neck ultrasound, are detecting usually small thyroid nodules which are not clinically apparent yet may be cancer. Neck pain is rarely a symptom of a thyroid tumor but may be due to thyroiditis, one of several lesions which may mimic or predispose the patient to thyroid cancer. Any of these clinical scenarios deserve appropriate investigation and diagnosis.

The most common initial finding is the appearance of a painless mass in the lower anterior neck in the region of the thyroid gland. The primary-care physician is usually consulted and the presence of the mass or nodule confirmed. At this point the patient should have an appropriate history taken with particular reference to those questions relating to increased risk of thyroid cancer. At the same visit the neck should be carefully examined and the mass identified and its characteristics noted and described. What is its size? Is it painless or painful? What is its nature? Is it solitary or multiple, is it solid or cystic, is it soft or hard? Does the mass move up and down when the patient swallows? If not, it is most likely not of thyroid origin. Usually these characteristics can be ascertained and may assist in making a provisional diagnosis. Are speech and swallowing normal? These are secondary aspects of the condition, abnormalities of which may be of diagnostic significance. If the patient’s voice is abnormal the larynx (voice box) should be visualized either by the primary physician or a consultant who is familiar with the examination and is capable of doing it. Both sides of the neck should be carefully examined to ascertain if there are any other swellings or masses which could possibly be related to the primary thyroid abnormality. These may represent enlarged lymph nodes harboring metastatic tumor from the thyroid primary. While none of these abnormal signs or symptoms is diagnostic of thyroid cancer in and of itself, the presence of one or more should certainly raise the physician’s index of suspicion. While the initial examination may be limited to the neck, the patient should ultimately have a complete history taken and physical examination performed if thyroid cancer is diagnosed and before any surgical intervention is carried out.

What diagnostic tests should be initially performed? Since most thyroid nodules are benign, the challenge is to identify those that are malignant. There are no thyroid blood tests or imaging studies which can reliably differentiate between benign and malignant thyroid nodules. A measure of the thyroid’s physiological function is important to exclude over- or under- activity of the gland. Either of these endocrinological conditions may contraindicate immediate thyroid surgery and anesthesia. Thyroid ultrasound will accurately and graphically illustrate the size, outline and consistency of the gland, but cannot distinguish between benign or malignant nodules. Radioactive iodine scans of the neck will document the location and general size of the isotope-concentrating thyroid but not as precisely as will the ultrasound and that portion of the gland which does not concentrate the radioisotope will not be visualized. It does provide a measure of the gland’s ability to “pick-up” or concentrate the radioactive isotope, a gross measure of thyroid function. Most thyroid tumors, benign and malignant, will not concentrate the isotope but, on the contrary, a small portion of tumors that do so may be malignant. Thus the radioactive isotope scan provides little help in distinguishing between benign and malignant tumors. Other diagnostic studies may be indicated depending upon the clinical status of the tumor and the patient.

The most reliable and specific diagnostic test for the evaluation of a thyroid nodule or mass is a fine needle aspiration biopsy. It is easily performed, requires no special or expensive equipment, usually is well tolerated with little or no discomfort, and provides the only specific method of pathologic diagnosis of the thyroid abnormality short of open surgery. Most primary-care physicians will not be prepared to perform this test but will refer the patient to an appropriate specialist, either endocrinologist or surgeon. While a small percentage of biopsies may be inconclusive, a repeat biopsy may resolve the question or indicate the need for further study and treatment.

The primary treatment of choice for most thyroid tumors is surgical removal. Once the examination is complete and surgery is indicated, an experienced thyroid surgeon should be consulted. This may be a general surgeon, an otolaryngologist (ear, nose and throat specialist) or endocrine surgeon, usually a general surgeon who has confined his/her practice to the treatment of endocrine tumors. In general, the more experienced the surgeon in the management of thyroid tumors, the more sophisticated and knowledgeable he or she is in the decision making, surgical technical ability and pre- and post-operative patient care. The pathologic examination of any thyroid surgical specimen is very important and demanding. There are multiple pitfalls encountered in deriving a precise and accurate diagnosis. That diagnosis significantly impacts upon subsequent investigation, treatment and ultimate prognosis. The more experienced the pathologist, the more likely the diagnosis will be accurate and complete.

The treatment of thyroid cancer is often a co-operative effort requiring several different specialists including endocrinologist, nuclear medicine expert, medical and radiation oncologist in addition to the primary care physician and surgeon. Treatment must be individualized at multiple points along the patient’s course, depending upon the nature and extent of the tumor, while not excluding factors of the patient’s general health, both physical and psychological, age and wishes. The complex management of the more aggressive tumor may require several different treatment modalities to provide the patient the best chance of cure with the best quality of life. The importance of one physician who is knowledgeable and sophisticated in the management of thyroid cancer to act as the captain of the ship, directing the treatment and enlisting the aid of other disciplines when and if necessary, cannot be overemphasized. Most, but not all, patients will do well if the disease is detected early and managed appropriately and carefully.

In summary, once a thyroid mass is detected, medical attention should be promptly sought. The pertinent history and physical examination should confirm the presence of a thyroid abnormality and its extent. Initial laboratory studies should include an assessment of thyroid function and a fine needle aspiration biopsy of the thyroid mass. Other blood and imaging studies may be indicated to further evaluate the situation leading to a presumptive diagnosis and appropriate treatment, usually surgery. Further treatment, if any, will be dictated by the final pathologic diagnosis and extent of disease and may require additional treatment modalities. Most patients with the most common thyroid cancer will do well but all will require lifelong observation and follow up.