Systematic Review of Recurrence Rate after Hemithyroidectomy for Low-Risk Well-Differentiated Thyroid Cancer

Background: Surgical extent in the management of well-differentiated thyroid cancer (DTC) remains a recurrent subject of debate. This is especially relevant in low-risk DTC of 1-4 cm, which represent the majority of new thyroid cancer diagnoses. With trends towards treatment de-escalation and recent guidelines from the American Thyroid Association and British Thyroid Association endorsing hemithyroidectomy (HT) alone for low-risk DTC of 1-4 cm, we sought to systematically appraise the literature to examine recurrence rate outcomes after HT in this low-risk group. Summary: Searching PubMed, Cochrane Library, and Ovid MEDLINE, we conducted a systematic review to assess the survival and recurrence rate data presented in all published studies that had a cohort of patients treated with HT for the treatment of DTC. Pooled 10-year survival and recurrence rates, odds ratios, and 95% confidence intervals were calculated for meta-analysis. We identified 31 studies (with a total of 228,746 patients (HT: 36,129, total thyroidectomy, TT: 192,617), which had published recurrence and/or survival data for patients having had HT for DTC. We discovered a pooled recurrence rate of 9.0% for HT, which is significantly higher than in previously published reports. Further, this rate is maintained when examining patients within low-risk cohorts established with recognised risk classifications. We also discovered that of those patients who develop recurrent disease, 48% recur outside the central neck. Key Messages: Our study provides a comprehensive systematic review of evidence aimed primarily at defining the recurrence rate in DTC after HT, and more specifically within the low-risk subgroup. We describe pooled recurrence and 10-year survival rates from a larger, broader, and more contemporary patient population than has been previously reported. Our findings indicate that there is a small but significantly higher recurrence rate after HT than TT, but the evidence base is heterogenous and subject to confounding factors and would ultimately benefit from prospective randomised trials to overcome these deficiencies.