September 21, 2015
2 min read

Gene expression classifier identifies benign thyroid nodules

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The Afirma gene expression classifier accurately identified benign thyroid nodules when fine-needle aspiration biopsy results were inconclusive, according to recent study findings published in The Journal of Endocrinology & Metabolism.

“The clinical use of the Afirma gene expression classifier continues to grow based on the robust validation trial data published in the New England Journal of Medicine in 2012 showing that it improves the preoperatively diagnosis of thyroid nodules with indeterminate cytology,” Trevor E. Angell, MD, an endocrinologist at Brigham and Women’s Hospital, told Endocrine Today. “However, there are few data regarding the long-term outcomes of thyroid nodules with benign [gene expression classifier] results. Our research addressed this important gap in our knowledge and evaluates if it is indeed acceptable to monitor patients with cytologically benign nodules during long-term follow-up.”

Trevor Angell

Trevor E. Angell

Angell and colleagues evaluated 90 patients with 95 cytologically indeterminate/gene expression classifier (GEC) benign (Cyto-I/GEC-B) thyroid nodules.

Ultrasound follow-up was available for 58 Cyto-I/GEC-B nodules in 56 adults (mean age, 58.4 years; 82.1% women) over a median of 13 months. For comparison, researchers evaluated 873 adults (mean age, 53.9 years; 89.3% women) with 1,224 cytologically benign (Cyto-B) thyroid nodules.

Main outcomes were nodule growth of 20% or more in two dimensions or 50% or more in volume, changes in sonographic features, as well as rates of repeat fine-needle aspiration (FNA), thyroidectomy and malignancy.

The numbers of nodules exhibiting growth of 20% of more were similar for Cyto-I/GEC-B nodules (8.6%) and Cyto-B nodules (8.3%). Also, 17.2% of Cyto-I/GEC-B nodules grew compared with 13.8% of Cyto-B nodules using the 50% or more volume growth criterion (P = .44).

Ninety-one percent of Cyto-I/GEC-B nodules did not have suspicious sonographic nodule features.

Repeat FNA assessments were performed in more patients in the Cyto-B group (16.8%) compared with the Cyto-I/GEC-B group (6.9%; P < .05).

Thyroidectomy was performed in more patients in the Cyto-I/GEC-B group (13.8%) compared with the Cyto-B group (0.9%; P < .0001). Four nodules were malignant in the Cyto-B group compared with one in the Cyto-I/GEC-B group (P = .16).

“Indeterminate nodules with a benign Afirma result show similar growth and ultrasound characteristics to cytologically benign nodules during long-term follow-up,” Angell said. “Furthermore, when such nodules are resected, they prove rarely malignant. These data strongly suggest that nonsurgical managmenet for such nodules is appropriate.” – by Amber Cox

Disclosure: The researchers report no relevant financial disclosures.