OP10 – Long-term outcome and postoperative morbidity in 1376 adults with AJCC pT1a papillary thyroid microcarcinoma (PTM) consecutively treated during eight deades at Mayo Clinic: is primary surgery curable and what is the optimal extent of thyroid resection?

      Hay, Ian1; Johnson, Tammi1; Kaggal, Suneetha2; Iniguez-Ariza, Nicole1; Reinalda, Megan2;Thompson, Geoffrey3 1 Division of Endocrinology, Mayo Clinic, Rochester, Minnesota, USA 2 Division of Biostatistics, Mayo Clinic, Rochester, Minnesota, USA 3 Division of Endocrine Surgery, Mayo Clinic, Rochester, Minnesota, USA   Background: Current ATA Guidelines recommend unilateral lobectomy (UL) as primary treatment for adult PTM. We identified 1376 PTM patients treated during 1936-2015 and defined outcome and morbidity associated with UL or bilateral lobar resection (BLR). Methods: We studied 1376 patients followed for mean 15.4 yr. Tumor recurrence (TR) and cause-specific mortality (CSM) rates were derived from a computerized database. Results: Median tumor size was 7 mm. 1.3% had extra-thyroid invasion. 27% were multifocal. 29% were pN1. 84% underwent BLR; 15% UL. Regional nodes were removed in 55%.  1369 patients (99.5%) were considered to have potentially curable PTM (pcPTM); 189 (14%) had remnant ablation (RA). Postoperatively, no patient undergoing UL had permanent unilateral cord paresis (PUCP) or permanent hypoparathyroidism (PH). After BLR, 6 (0.5%) had PUCP; 53 (5%) had PH. Overall survival did not differ from expected for an age and gender-matched control group (p=0.10). Only 4 patients (0.3%) died of PTM; 20-and 30-yr CSM rates were 0.3 and 0.7%.  In pcPTM 20- and 40- year TR rates (TRR) were 7 and 10%. 30-year locoregional RR after UL was 7.1%; after BLR, comparable rate was 6.9% (p = 0.87). 30-year TRR in pN1 cases was 21.8% after UL, indifferent from 22.5% observed after BLR and RA (p=0.99). Conclusions: In adult PTM, neither BLR nor RA significantly reduces RR, when compared to UL.  Higher morbidity occurs after BLR. Perhaps it is overdue to modify our treatment policies and employ UL when surgery, and not observation or ethanol ablation, is chosen for PTM.


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