Genetic Judgment: It’s Not Cancer

Benign thyroid nodules may be identified with gene signature

(RxWiki News) Doctors don’t know why abnormal growths called nodules commonly show up on the thyroid. These growths are often nothing to worry about, but sometimes they are cancerous.

Determining which nodules are actually cancerous tumors has been challenging.

Scientists have uncovered what’s called a "gene signature" which may help identify benign (not cancerous) nodules.

This "gene signature" test, which is still being studied, may result in fewer people having unnecessary tests and surgery to diagnose thyroid cancer.

"Learn about the tests used to diagnose your cancer."

Hernan Gonzalez, MD, PhD, associate professor at the Pontifical Catholic University of Chile in Santiago, led the study that identified ten different genes which tend to be present in benign nodules.

Located at the front of the neck, the thyroid helps to regulate a person’s metabolism, or how the body turns food into energy. Thyroid nodules can cause lumps in the neck, difficulty breathing or swallowing, hoarseness and other symptoms.

To test these growths, a procedure called a fine needle aspiration biopsy is used to take tiny tissue samples that are examined under a microscope to look for cancer.

Between 20 and 25 percent of thyroid biopsies generate unclear results, according to the authors.

"The management of the thyroid nodule is challenging, especially when the fine needle aspiration biopsy is indeterminate," D. Gregory Farwell, MD, FACS, Director of Head and Neck Surgery and Microvascular Surgery at the University of California, Davis, told dailyRx News. "Recently, efforts have been made to increase the predictive capability of biopsies with the addition of genetic testing looking at common mutations and genetic abnormalities found in thyroid cancers. To date, these have shown some promise but have persistent limitations in making an accurate diagnosis in all patients."

Dr. Farwell continued, "The standard of care for a definitive diagnosis in a suspicious, or indeterminate nodule is thyroid surgery where the entire specimen is submitted for pathology. In high volume centers, this is a very low-risk procedure; however, there are still infrequent surgical and anesthesia complications, and certainly costs from surgery to remove benign nodules."

For this study, the researchers scoured medical literature to find 18 genes that are associated with thyroid cancer. From here, the field was narrowed to 10 genes, and the scientists developed a computer program designed to classify thyroid nodules as benign or cancerous.

Using this system, the researchers tested tissue from 300 patients. Study participants included healthy individuals and patients with papillary thyroid cancer, the most common form of this type of cancer.

The test proved to be very accurate, correctly distinguishing between cancerous and non-cancerous tissue 93 percent of the time.

"We have developed a new highly predictive gene signature that accurately classifies thyroid nodules. It effectively classifies benign nodules, making it potentially useful to identify patients that do not require surgery," the study authors wrote.

"Efforts such as the ones described in this abstract hold promise for limiting the number of surgeries in patients with benign nodules," Dr. Farwelll said. "However, until larger, more comprehensive studies are completed, care should be taken in denying surgical treatment based on the preliminary data to date."

Findings from this study were presented at The Endocrine Society’s 95th Annual Meeting in June. A biomedical research consortium in Santiago funded the study.

All research is considered preliminary before it’s published in a peer-reviewed journal.

Reviewed by: 
Review Date: 
June 18, 2013