OBJECTIVES: In January 2016, the American Thyroid Association guidelines recommended hemithyroidectomy as initial treatment for smaller (1-4cm) primary thyroid carcinomas, particularly for papillary (PTC) and follicular thyroid cancer (FTC). This study evaluated the association between the guideline release and initial surgical procedures for patients with PTC/FTC tumors.

METHODS: Patients with PTC/FTC tumors 1-4cm who underwent hemithyroidectomy or total-thyroidectomy were identified from the 2009-2018 National Cancer Database. To avoid the bias from the evidence regarding hemithyroidectomy benefits before the guideline release, we used 2009-2011 as baseline and estimated hemithyroidectomy utilization in the following years, 2016-2018 were considered as post-guideline. A linear probability model was used to assess trends in hemithyroidectomy over time, adjusting for patient, disease, and hospital characteristics. We further conducted a stratified analysis by adding the interaction between year and hospital type, which included community cancer programs (CCP), comprehensive community cancer programs (CCCP), academic/research programs (ARP), and integrated network cancer programs (INCP).

RESULTS: The final study cohort included 69,455 patients, of whom 11.34% received hemithyroidectomy and 88.66% received total thyroidectomy. Hemithyroidectomy utilization did not change significantly from 2012-2015 relative to the 2009-2011 baseline. Following the guideline release, however, Hemithyroidectomy utilization increased significantly in 2016 (1.2%, p=0.004), 2017 (3.5%, p<0.0001), and 2018 (7.2%, p<0.0001). The stratified analysis showed significant differences in timing of the shift to hemithyroidectomy by hospital type. Hemithyroidectomy utilization significantly increased beginning in 2014 for ARP (p<0.0001) and INCP (p<0.0001), in 2015 for CCCP (p<0.0001), and in 2016 for CCP (p<0.0001).

CONCLUSIONS: Although hemithyroidectomy utilization among patients with PTC and FTC tumors 1-4cm significantly increased following the 2015 ATA guideline, the guideline does not appear to be the catalyst for most hospitals. Research focused cancer centers began increasing hemithyroidectomy two years before the guidelines were released, and only CCP hospitals began to increase hemithyroidectomy utilization following the guideline release.