Papillary Thyroid Microcarcinoma in Adult Patients: How Does Outcome and Morbidity after an Initial Unilateral Thyroid Lobectomy Compare to a More Conventional Approach of Near-Total or Total Thyroidectomy and Selective Radioactive Iodine Remnant Abalation?
Presentation Number: OR22-4
Date of Presentation: April 2nd, 2016
Ian D Hay*, Tammi R Johnson, Suneetha Kaggal, Megan S Reinalda, Thomas J Sebo and Geoffrey B Thompson
Mayo Clinic College of Medicine, Rochester, MN
Background. The rising thyroid cancer (TC) incidence rates seen in high-resource countries (Thyroid 25:1127, 2015) are restricted to patients with small papillary TCs (PTCs). SEER data demonstrates that 12.3% of TC-related deaths are associated with PTCs with tumor diameters of 2cm or less, despite undergoing thyroidectomy (Cancer 121: 1017, 2015). The recently released 2015 American Thyroid Association Guidelines have recommended a unilateral lobectomy (UL) as the initial surgical procedure for adult patients with papillary thyroid microcarcinoma (PTM). Our present analysis identified a 1941-2010 adult PTM cohort managed at our institution, and aimed to define long-term postoperative outcome (mortality and recurrence) and morbidity associated with an initial definitive surgical approach consisting of either UL or bilateral lobar resection (BLR).
Methods. We studied 1153 patients (814 women, 339 men; median age 48 years), who were aged more than 18 years at time of surgery and were consecutively treated during seven decades. Mean follow-up was 17.3 years and ranged to 61 years. Tumor recurrence (TR) and cause-specific mortality details were derived from an institutional computerized database.
Results. Median tumor size was 7 mm (range 0.08-1.0 cm). 15 (1.3%) had gross extra-thyroid invasion; 298 tumors (26%) were multifocal. 358 (31%) had pN1 neck nodes; 4 (0.3%) had initial distant metastases. 982 (85%) underwent BLR; 80% near-total or total thyroidectomy (NT/TT). 161 (14%) had unilateral lobectomy (UL). Regional nodes were removed by “node picking” (23%) or compartmental dissection (32%). Postoperatively, no UL patient had permanent unilateral cord paresis (PUCP) or permanent hypo-parathyroidism (PH). After BLR, 0.7% had PUCP; 4% had PH. Overall survival did not differ from expected for an age- and gender-matched control group; 397 deaths observed versus 431 expected (p=0.10). Only 4 patients (0.3%) died of PTM. In 1,148 patients with potentially curable PTM (pcPTM: i.e. no distant spread at diagnosis and no gross residual disease), 10-, 20-, and 40-year TR rates (TRR) were 6, 7 and 10%, respectively; 20-year rates for neck nodal metastases, local recurrences and distant metastases were 5.7%, 1.4% and 0.4%, respectively. 30-year loco-regional recurrence rate (LRR) in pcPTM after UL was 7.2%; after BLR (n=977) or NT/TT (n=785) comparable rates were 7.0% (p=0.90) and 7.9% (p=0.86). 30-year LRR in pN1 NT/TT cases, who underwent radioiodine remnant ablation (RRA), was 20% and was 27% after UL without RRA (p=0.57).
Conclusions. In adult PTM, neither NT/TT nor RRA significantly reduces recurrence rates, when compared to UL. Higher morbidity (PUVP, PH) occurs after NT/TT. Perhaps it is overdue for institutions like ours to individualize our treatment policies and more routinely employ UL when surgery, and not observation or ultrasound-guided ethanol ablation, is chosen for PTM patients.
Nothing to Disclose: IDH, TRJ, SK, MSR, TJS, GBT