Prophylactic Lateral Neck Dissection for Medullary Thyroid Carcinoma is not Associated with Improved Survival

BACKGROUND: Patients with medullary thyroid carcinoma (MTC) often receive lateral lymph node dissection with total thyroidectomy when calcitonin levels are elevated, even in the absence of structural disease, but the effect of this intervention on disease specific outcomes is not known. METHODS: We retrospectively reviewed patients from 1986 to 2017 who underwent thyroidectomy with curative intent for MTC at our institution. The association of disease specific survival (DSS) and clinicopathologic features was examined using univariate and multivariate Cox regression. RESULTS: We identified 316 patients who underwent curative resection for medullary thyroid carcinoma. Overall and disease specific survival were 76% and 86% at 10-years. To investigate the effect of prophylactic ipsilateral lateral lymph node dissection, we analyzed 89 patients without known structural disease in the neck lymph nodes at the time of resection and preoperative calcitonin > 200 pg/ml, of which 45 had an ipsilateral lateral lymph node dissection (LND) and 44 did not. There were no differences in tumor size or preoperative calcitonin levels. There was no difference at 10 years in cumulative incidence of recurrence in the neck (20.9% LND vs 30.4% no LND, p=0.46), cumulative incidence of distant recurrence (18.3% vs 18.4%, p=0.97), disease specific survival (86% vs 93%, p=0.53), or overall survival at (82% vs 90%, p=0.6). CONCLUSION: Lateral neck dissection in the absence of clinical or radiologic abnormal lymph nodes is not associated with improved survival in patients with MTC.