The Price of Less Surgery: Completion Thyroidectomy After Lobectomy for Low-Risk Papillary Thyroid Carcinoma

Background Optimal surgical extent for cT1-2N0 papillary thyroid carcinoma (PTC) remains debated. Methods This study included 400 consecutive low-risk cT1-2N0 PTC patients (tumor ≤4 cm, clinically node-negative) who underwent initial total thyroidectomy (TT, n = 250) or lobectomy (LT, n = 150) between 2020 and 2024. The primary descriptive outcome was completion thyroidectomy rate in the LT group; the primary oncologic outcome was recurrence-free survival (RFS). Multivariable regression and propensity score matching identified predictors and adjusted comparisons. Results TT was associated with longer operative time, hospital stay, and drainage volume (all P < 0.001). Temporary and permanent hypoparathyroidism were significantly higher after TT (25.2% vs 3.3%; 6.0% vs 0.7%, both P < 0.01), with TT as independent risk factor. At median 36.2 months, RFS favored TT (adjusted HR = 0.37, P = 0.012); however, given only 21 recurrence events, this finding is exploratory. Among LT patients, 34.7% (52/150) ultimately required completion thyroidectomy due to pathologic upgrade. Independent predictors were tumor size (OR = 3.19/cm), multifocality (OR = 4.81), and positive lymph node count (OR = 2.61/node) (all P < 0.01). While tumor size is preoperatively assessable, multifocality and nodal burden are predominantly postoperative findings guiding risk stratification. Conclusions The oncologic safety of lobectomy for low-risk PTC is well-established. The key tradeoff is clear: lobectomy markedly reduces permanent hypoparathyroidism (0.7% vs 6.0%) but carries a one-in-three reoperation risk, predicted by tumor size, multifocality, and nodal burden. Although TT showed an exploratory RFS benefit, this finding requires confirmation. These tradeoffs must be explicitly discussed during preoperative counseling to enable informed, preference-sensitive decision-making.