Optimal extent of thyroidectomy in clinically node-negative unilateral papillary thyroid carcinoma >1 cm and ≤4 cm

Abstract

Background: The optimal extent of thyroidectomy for papillary thyroid carcinoma (PTC) measuring >1 cm and ≤4 cm remains a subject of debate. This study aimed to determine the optimal surgical extent for clinically node-negative (cN0) unilateral PTC measuring >1 cm and ≤4 cm and to identify factors associated with recurrence risk. Methods: We conducted a retrospective analysis of 403 patients with unilateral cN0 PTC measuring 11–40 mm. Propensity score-matched (PSM) analysis was performed using five covariates including age, sex, tumor size, central neck dissection, and follow-up duration. Patients were stratified by tumor size (11–20 vs. 21–40 mm), degree of extrathyroidal extension (ETE) (none, minimal, and invasion into the strap muscle), and surgical extent (lobectomy vs. total thyroidectomy). Recurrence and survival outcomes were compared. Results: In the baseline cohorts, among the 403 patients, 304 had 11–20 mm tumors, and 99 had 21–40 mm PTC. Total thyroidectomy was performed in 65.3% of cases. Rates of minimal ETE and strap muscle invasion were 41.4% and 8.2%, respectively. Recurrence rates did not differ significantly by tumor size, ETE status (except strap muscle invasion), or surgical extent. Strap muscle invasion independently predicted recurrence [hazard ratio (HR) =6.380, P=0.01] and was associated with poorer disease-free survival. After PSM, 88 pairs of patients were generated in the lobectomy and total thyroidectomy groups. In the PSM cohort, the recurrence rate did not differ between the two groups. However, the overall complication rate was significantly higher in the total thyroidectomy group (49.5% vs. 24.8%, P=0.009), largely driven by a higher rate of transient hypoparathyroidism (39.1% vs. 7.6%, P<0.001). Conclusions: In patients with unilateral cN0 PTC measuring 11–40 mm, lobectomy may serve as an appropriate primary surgical option, providing disease control comparable to total thyroidectomy while reducing procedure-related complications, except in those with strap muscle invasion.