THYROID NODULE – A Common Problem Now More Easily Resolved

The thyroid gland is located in the central, lower portion of the neck above the breast bone. It produces thyroid hormone, which is needed for your body’s tissues and organs to work normally and for you to feel well. Thyroid nodules are lumps that occur in the thyroid gland.

Thyroid nodules are common in the United States population. Roughly one in every three adults (more common in females) has one or more nodules. About 95 percent are benign and very small. Benign nodules only occasionally enlarge or cause symptoms such as pain, tenderness, neck pressure or trouble swallowing. A thyroid nodule may be detected after noticing fullness or swelling in the lower, central neck or picked up on a routine physical examination. When a nodule is discovered during an x-ray examination such as a CAT (CT) scan of the neck or chest being done for reasons unrelated to the thyroid, it is called an “incidental” finding. Because medical imaging procedures are being used more than they use to be, incidentally discovered thyroid nodules have become quite common. Regardless of how a nodule is detected, for further evaluation a thyroid ultrasound and a blood test to check how the thyroid is working (serum Thyroid Stimulating Hormone or TSH) are recommended.

An ultrasound provides important information about nodules in particular and the entire thyroid gland in general, including its size. Seventy to 75 percent of nodules can accurately be called benign on the basis of an ultrasound. The others will have some features that are sometimes seen with thyroid cancer, such as an irregular shape or certain types of calcium deposits and blood flow patterns. These nodules usually require a fine needle aspiration (FNA) biopsy in order to determine whether or not they are cancer. During 2012, there will be more than 500,000 FNAs performed, and the American Cancer Society estimates more than 56,000 new thyroid cancers will be discovered by FNA.

An FNA biopsy is usually performed by an endocrinologist who is trained to evaluate and take care of patients with thyroid diseases. Sometimes a radiologist or a surgeon performs thyroid FNAs. An FNA is typically performed with a 25 or 27 gauge needle, which is smaller than the needles used to draw blood, creates little discomfort and provides enough cytological material (cells) to make a diagnosis.

About 80 to 85 percent of FNA cytology (study of cells under a microscope) results are benign. Although this is quite reassuring, a few percent of the time the result may be wrong. Therefore, periodic follow-up is still required in order to make sure that the nodule is stable and that the report is correct. The other 15 to 20 percent – or one in every five or six of thyroid nodules that are not read as benign – are called “indeterminate,” which means that it is not certain whether the nodule is benign or cancer. This year alone, there will be up to 90,000-100,000+ patients with “indeterminate” FNAs. Until recently, even though almost two-thirds of these nodules turn out to be benign, surgical removal of half or more of the thyroid gland done under general anesthesia has been the only way to figure out whether these nodules are benign or cancer.

PROMISING NEW DEVELOPMENT

Recent scientific advances in the field of genomics (study of genes) show great promise for more accurately predicting prior to surgery whether an “indeterminate” nodule is benign or cancer. Newly developed techniques are used to analyze FNA material for “molecular markers,” genetic material or the products of genes that are found in many thyroid cancers or benign thyroid nodules. Preliminary studies suggest that by combining these tools with standard cytology the approach to “indeterminate” nodules may change. The number of surgical procedures for “indeterminate” nodules that are benign, and do not have to be removed, would be reduced. On the other hand, when cancer is highly likely the entire thyroid would be removed—the standard approach for thyroid cancer—rather than just one side to diagnose cancer followed by a second operation at a later date.

For more information about thyroid nodules and these new tests, ask your endocrinologist and check out the following websites: www.veracyte.com (Afirma® Gene Expression Classifier test) and www.asuragen.com (miRInform® test).

Dr. Daniel S. Duick was a member of the staff of Mayo Clinic (Rochester, MN) before relocating to Phoenix, Arizona, where he served as Director of the Internal Medicine Residency Training Program for 12 years at St. Joseph’s Hospital and Medical Center. He then joined Endocrinology Associates in private practice in Phoenix. A consultant to Asuragen, Inc. and Veracyte, Inc. Dr. Duick is a past AACE president and the immediate past president of the American College of Endocrinology.