Risk Stratification and Long-Term Outcome of Benign Thyroid Nodules - An 11-Year Cohort Study.

Abstract

Objectives: The recommended follow-up interval and length, as well as the indication for repeat fine needle aspiration in benign nodules remains unclear up to date. The purpose of the study was to evaluate the long-term follow-up and management outcomes of benign thyroid nodules.

Methods: A retrospective study included 1224 nodules from 1071 patients with initial benign thyroid nodules, between 2010 and 2014. Phone calls were made to obtain updated information from patients when information was missing. The main outcome of the study was a change in the nodule's risk of malignancy (ROM) - defined either as a malignant pathology (when obtained) or by cytology (repeated Bethesda System for Reporting Thyroid Cytopathology III, IV, V, or VI). Secondary outcomes included the yield of repeated fine-needle aspiration (FNA). Data included demographics, sonographic data, follow-up adherence, repeat FNA results, surgery types, and pathologic results.

Results: The average follow-up period was 9.48 ± 1.72 years. 0.65% (7/1071) of patients remained without follow-up. The ROM was 3.43% (42/1224). Benign nodules >2 cm had a higher ROM compared to smaller nodules (5.3% vs 1.3% respectively, P-value<.001). Repeat FNA and a change in nodule size did not significantly change ROM. Among the 41 malignant nodules with documented size, 33 (80.49%) were nodules larger than 2 cm. A total of 35 cases (85.37%) were diagnosed within the first 3 years of follow-up.

Conclusion: ROM for benign nodules remains considerably low, especially for nodule smaller than 2 cm. Long-term follow-up and repeated FNA and follow-up for BTSC II thyroid nodules without suspicious features should be reconsidered.