Abstract
IMPORTANCE: Total thyroidectomy is the established surgical standard for hereditary and sporadic medullary thyroid cancer (sMTC). However, for unilateral sporadic tumors, its benefit over lobectomy remains uncertain. OBJECTIVE: To compare oncologic outcomes between total thyroidectomy and lobectomy in patients with sMTC. DATA SOURCES AND STUDY SELECTION: MEDLINE, Embase, Scopus, and Cochrane Central Register of Controlled Trials were searched from inception to December 2025 to identify comparative studies on patients with sMTC who underwent total thyroidectomy or lobectomy. DATA EXTRACTION AND SYNTHESIS: Reviewers working independently and in duplicate screened titles, abstracts, and full-text articles for eligibility using standardized instructions. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and Meta-Analysis of Observational Studies in Epidemiology (MOOSE) guidelines were used for reporting. MAIN OUTCOMES AND MEASURES: Primary outcomes were mortality, overall survival, structural recurrence, biochemical cure, and distant metastasis development. The secondary outcome was postoperative complications. Effect measures were calculated as odds ratios (ORs) or relative risks (RRs) with 95% CIs using a random-effects model. The risk of bias was assessed using the Newcastle-Ottawa Scale. RESULTS: Nine retrospective studies met inclusion criteria and comprised 1371 patients (295 of 397 patients [74.3%] with documented sex were female, and median age ranged from 45.0 to 58.2 years). A total of 531 patients (38.7%) underwent lobectomy and 840 (61.3%) underwent total thyroidectomy. Of 341 tumors, 280 (82.1%) lacked extrathyroidal extension, 284 of 401 tumors (70.8%) measured smaller than 2 cm (70.8%), and 197 of 343 tumors (57.4%) were node negative; central neck dissection was performed in 445 of 492 patients (90.4%). Multifocal disease was uncommon and reported in 30 of 330 patients (9.1%). Mortality did not differ at 5 years (RR, 0.30; 95% CI, 0.07-1.35) or beyond (RR, 1.00; 95% CI, 0.40-2.47). Overall survival at 5 years was similar (RR, 1.02; 95% CI, 0.94-1.11). Total thyroidectomy was not associated with lower structural recurrence rates at 5 years (OR, 0.45; 95% CI, 0.14-1.49), but it was associated beyond 5 years (OR, 7.26; 95% CI, 1.07-49.21). No differences were observed for biochemical cure at 5 years (OR, 0.86; 95% CI, 0.47-1.56) or beyond 5 years (OR, 0.87; 95% CI, 0.26-2.89). Distant metastasis development did not differ at 5 years (OR, 1.64; 95% CI, 0.09-31.52). Sensitivity analyses revealed no differences across any outcomes. Postoperative complications were more common in total thyroidectomy. Risk of bias was high in 4 studies, moderate in 4, and low in 1. CONCLUSIONS AND RELEVANCE: Findings in this systematic review and meta-analysis, based on data from retrospective studies, suggest that thyroid lobectomy may be associated with oncologic outcomes comparable to total thyroidectomy in selected patients with sMTC.