Molecular panel increases likelihood that initial surgery for thyroid cancer is corrective
Routine use of a molecular testing panel greatly decreased the need for an initial lobectomy to confirm diagnosis in patients with thyroid nodules and cancer, reported researchers. The test improved the chances of patients undergoing the correct initial surgery by 30%.
“Before this test, [approximately] 1 in 5 potential thyroid cancer cases could not be diagnosed without an operation to remove a portion of the thyroid,” said lead author Linwah Yip, MD, assistant professor of surgery at the School of Medicine of the University of Pittsburgh and surgical oncologist at the University of Pittsburgh Medical Center in Pennsylvania. Previously, if cancer was found in the portion removed during the initial thyroid lobectomy, a second surgery was needed to remove the remainder of the gland. This molecular testing panel bypasses the need for a diagnostic lobectomy, allowing surgeons to correctly identify and completely remove the cancerous thyroid in one procedure. This reduces risk and stress to the patient, as well as recovery time and costs.
Cancer of the thyroid is now the fifth most common cancer diagnosed in women. Thyroid cancer is one of the few cancers that continue to increase in incidence, although the 5-year survival rate is 97%.
Previously, the most accurate form of testing for thyroid cancer was a fine-needle aspiration biopsy, where a doctor guides a thin needle to the thyroid and removes a small tissue sample for testing. However, in 20% of these biopsies, cancer cannot be ruled out. A lobectomy, in which half of the thyroid in removed, is then needed to diagnose or rule out thyroid cancer. In the case of a postoperative cancer diagnosis, a second surgery is required to remove the rest of the thyroid.
Researchers have identified certain gene mutations that are indicative of an increased likelihood of thyroid cancer, and the molecular testing panel developed at UPMC can be run using the sample collected through the initial, minimally invasive biopsy, rather than a lobectomy. When the panel shows these mutations, a total thyroidectomy is advised.
Yip and her colleagues followed 671 UPMC patients with suspicious thyroid nodes who received biopsies. Approximately half the biopsy samples were run through the panel, and the other half were not. Patients whose tissue samples were not tested with the panel had a 2.5-fold higher statistically significant likelihood of having an initial lobectomy and then requiring a second operation. The study was published in the Annals of Surgery (2014; doi:10.1097/SLA.0000000000000215).
In 2009, the American Thyroid Association (ATA) revised its guidelines to add that doctors may consider the use of molecular markers when the initial biopsy is inconclusive.
“The ATA is currently revising those guidelines to take into account the latest research, including our findings,” said senior author Sally Carty, MD, Pitt professor of surgery, co-director of the UPMC/UPCI Multidisciplinary Thyroid Center and recent president of the American Association of Endocrine Surgeons. “The molecular testing panel holds promise for streamlining and eliminating unnecessary surgery not just here but nationwide.”