Genetic Tool Identifies Benign Thyroid Growths

A new genetic test accurately and consistently diagnoses benign growths, or nodules, on the thyroid gland.

The thyroid gland sometimes develops small nodules and although these nodules are extremely common and usually benign, a small number are cancerous, which makes screening tests essential.

Endocrinologists at the Pontifical Catholic University of Chile (Santiago, Chile) developed a genetic test that accurately identified benign nodules in nearly all samples analyzed. Specifically, the test differentiated between cancerous and noncancerous tissue in 96% of thyroid samples.

To develop the gene signature test, the investigators conducted a literature search to identify 18 genes associated with thyroid cancer. They then selected 10 of these genes to develop a computer program that detects the presence of cancer in thyroid nodules. They used a sensitive DNA-amplifying test called polymerase chain reaction, and tested samples of thyroid nodules from 300 patients.

The problem with the currently available screening test is that it often yields inconclusive results. In 20% to 25% of these tests, the results are unclear. In addition to causing anxiety among patients, inconclusive tests lead to repeated tests to rule out cancer, or even to surgery, given that cancer is present in about 25% of inconclusive cases. As a result, three out of four patients have unnecessary surgery, leading to rising treatment costs and the risk of possible complications related to unnecessary medical procedures.

Hernan Gonzalez, MD, PhD, an associate professor at the Pontifical Catholic University, said, “We have developed a 'gene signature' that effectively identifies benign thyroid nodules. This test is potentially useful to identify patients who do not require surgery. For the general public, this is important since it will offer a diagnostic tool that will avoid thousands of surgeries, with a major impact in health costs, eliminating potential surgical complications and the need for permanent thyroid hormone supplementation. In addition, it should be widely available to local laboratories and hospitals and at a reasonable cost for the health system." The study was presented at The Endocrine Society's 95th Annual Meeting held June 15–18, 2013, in San Francisco, CA, USA).

Related Links:
Pontifical Catholic University of Chile