Hemithyroidectomy versus total thyroidectomy for patients with differentiated thyroid cancer: a systematic review and meta-analysis

Background: The 2015 American Thyroid Association (ATA) guidelines recommended hemithyroidectomy as an acceptable treatment for patients with differentiated thyroid cancer (DTC) tumors 1–4 cm. The primary objectives of this study were to trace the accumulation of evidence supporting hemithyroidectomy prior to the release of the 2015 ATA guidelines and to synthesize the available data on surgical outcomes for hemithyroidectomy and total thyroidectomy. Methods: PubMed was systematically searched for studies comparing hemithyroidectomy and total thyroidectomy among adult patients with DTC ≥1 cm, focusing on patient outcomes including recurrence rates, overall survival (OS), disease-free survival (DFS), and disease-specific survival (DSS). Fixed-effects or random-effects models were applied as appropriate to estimate risk ratios (RRs) and hazard ratios (HRs) based on the Woolf test. Cumulative meta-analyses were also performed to illustrate changes in pooled estimates as studies were added incrementally by year of publication. Results: The 14 studies, including 176,238 patients, were analyzed. Of these, 88.4% underwent total thyroidectomy and 11.6% (n=20,435) underwent hemithyroidectomy, with a mean follow-up time of 8 years. We found no significant differences between hemithyroidectomy and total thyroidectomy in recurrence rates [RR: 1.036, 95% confidence interval (CI): 0.698–1.538], OS (RR: 0.995; 95% CI: 0.985–1.006), or DSS (RR: 1.001; 95% CI: 0.998–1.005). Total thyroidectomy was associated with marginally better DFS compared to hemithyroidectomy (RR: 0.980, 95% CI: 0.963–0.997). Conclusions: This systematic review and meta-analysis found that total thyroidectomy was associated with slightly greater DFS relative to hemithyroidectomy, but no statistically significant differences were observed in recurrence, OS, and DSS between the two procedures. The accumulation of evidence supporting hemithyroidectomy may have prompted the ATA to revise their guidelines and encouraged surgeons to increasingly consider hemithyroidectomy as a safe procedure for treating patients with DTC ≥1 cm.