Afirma benign thyroid nodules show similar growth to cytologically benign nodules during follow-up

Abstract

Context: The Afirma gene expression classifier (GEC) is a molecular diagnostic test that has a high negative predictive value for ruling out malignancy in thyroid nodules with indeterminate cytology. Many patients with a cytologically indeterminate and GEC benign (Cyto-I/GEC-B) nodule undergo monitoring instead of diagnostic surgery, but few data describe their follow-up. Objective: The objective of the study was to determine the sonographic changes and clinical outcomes for patients with Cyto-I/GEC-B nodules compared with patients with cytologically benign (Cyto-B) nodules. Design: This was a retrospective analysis of consecutive Cyto-I/GEC-B nodules evaluated at Brigham and Women's Hospital compared with Cyto-B nodules. Main Outcomes: Nodule growth of 20% or greater in two dimensions or of 50% or greater in volume, change in sonographic features, and rates of repeat fine-needle aspiration, thyroidectomy, and malignancy. Results: Ninety-five Cyto-I/GEC-B nodules in 90 patients were identified. Five patients underwent primary surgical resection. Of the remaining 90 nodules, 58 (64.4%) had sonographic follow-up available at a median of 13 months (range 4-40 mo). Cyto-I/GEC-B nodules showed similar growth compared with 1224 Cyto-B nodules using either of the following criteria: 20% or greater in two dimensions (8.6% vs 8.3%, P < .80) or 50% or greater in volume (17.2% vs 13.8%, P