Lobectomy and completion thyroidectomy rates increase after the 2015 ATA Differentiated Thyroid Cancer Guidelines update

Background: The 2015 American Thyroid Association Guidelines(Guidelines) permit thyroid lobectomy(TL) or total thyroidectomy(TT) in the management of low-risk papillary thyroid cancer(PTC). As definitive risk-stratification is only possible post-operatively, some patients may require completion thyroidectomy(CT) after final histopathological analysis. Methods: A retrospective cohort study of patients undergoing surgery for low-risk PTC in a tertiary referral centre was undertaken. Consecutive adult patients treated from January 2013–March 2021 were divided into two groups (pre- and post-publication of Guidelines on 01/01/2016). Only those eligible for lobectomy under rule 35(B) of the Guidelines were included: Bethesda V/VI cytology, 1–4cm post-operative size, and without pre-operative evidence of extrathyroidal extension or nodal metastases. We examined rates of TL, CT, local recurrence and surgical complications. Results: There were 1488 primary surgical procedures performed for PTC on consecutive adult patients during the study period, of which 461 were eligible for TL. Mean tumour size (p=0.20) and mean age(p=0.78) were similar between time-periods. The TL rate increased significantly from 4.5% to 18% in the post-publication period(p<0.001). The proportion of TL patients requiring CT(43% vs 38%) was similar between groups. The overall proportion of patients requiring CT increased significantly from 1.9% to 6.9% in the post-publication period(p=0.023). There was no significant change in complications(p=0.55) or local recurrence rates(p=0.24). Conclusion: The introduction of the 2015 ATA guidelines resulted in a modest but significant increase in the rate of lobectomy for eligible PTC patients. In the post-publication period, 38% of patients who underwent TL ultimately required CT after complete pathological analysis.