R. Pudhucode1, H. Chen2, B. Lindeman2 1Alabama College of Osteopathic Medicine,Dothan, ALABAMA, USA 2University Of Alabama at Birmingham,Division Of Surgical Oncology, Department Of Surgery,Birmingham, Alabama, USA
Introduction:
Thyroid nodules are commonly found in clinical practice. Previously, it was routine for any nodule over 1.0 cm in size to undergo fine needle aspiration (FNA) biopsy. The American Thyroid Association (ATA) published new guidelines in 2015 that recommend thyroid nodule FNA biopsy be based on size plus ultrasound characteristics. In 2016, the American College of Radiology (ACR) introduced a different set of ultrasound-based guidelines called the Thyroid Imaging Reporting and Data System (TIRADS) to assess the need for biopsy of thyroid nodules. The ATA guidelines utilize a pattern-based approach to identify nodule characteristics associated with malignancy. The ACR TIRADS utilizes a point system to assess the degree of risk for malignancy of each ultrasound characteristic.
Methods:
This study aims to evaluate the recommendations for thyroid nodule FNA biopsy between the two scoring systems in a historical cohort of patients with a diagnosis of cancer on surgical pathology. Ultrasound characteristics, FNA biopsy, and surgical pathology results were evaluated for all patients with a diagnosis of thyroid malignancy treated at the University of Alabama at Birmingham (UAB) from 2010 – 2016. Patients with Graves’ disease, thyrotoxicosis, and incomplete records were excluded.
Results:
Of 285 thyroid nodules studied, 34.4% (n=98) were found to have discordant recommendations for FNA biopsy between the ATA and ACR systems. For all 98 discordant nodules, the ATA guidelines recommended biopsy, while the ACR system did not. Nodules <1.0 cm in size which would not be recommended for biopsy in either present-day classification system comprised 31.2% (n=89) of the study population. Excluding the 89 sub-centimeter nodules, 50% of patients with thyroid cancer would have been missed if the ACR system alone were used. On FNA biopsy, 59.0% of the discordant nodules were classified as malignant. Among nodules 1.0 – 1.4 cm in size, the ACR system missed 45 nodules (45.9%); 35 of which were malignant on final pathology (77.8%). For nodules 1.5 – 1.9 cm in size, 16 (16.3%) were missed by the ACR system, 15 of which were malignant (93.8%). Similarly, for nodules 2.0 – 2.4 cm in size, 9 out of 12 discordant nodules were malignant (75.0%). Lastly, for those nodules over 2.5 cm in size, 23 out of 25 discordant nodules (92.0%) were malignant on final pathology.
Conclusion:
If the ACR classification system alone had been utilized, 50% of patients with thyroid cancers 1.0 cm and larger treated at UAB between 2010 – 2016 would not have had their nodules biopsied. This could have resulted in delays in diagnosis and/or therapy for these patients.
