Objective  To study the optimum type of surgery for untreated medullary thyroid carcinoma.

  Methods  To retrospectively analyse the clinical data of 73 patients with untreated medullary thyroid carcinoma who received surgical treatment at our hospital. The patterns of neck metastases and the postoperative recurrence were investigated.

  Results  The rate of multifocal medullary thyroid carcinoma was 26.0 % (19 / 73). The overall cervical lymph node metastasis rate was 58.9 % (43 / 73). The central neck nodal metastasis rate was 52.1% (38 / 73). Ipsilateral and bilateral nodal metastasis rate was 53.4 % (39 / 73) and 11.0 % (8 / 73), respectively. The cervical occult metastasis rate in cN0 patients was 18.9 % (7 / 37). In multivariate analysis, central neck nodal metastasis remained an independent risk factor of ipsilateral nodal metastasis and primary T4 was an independent risk factor of contralateral lateral nodal metastasis. The loco-regional recurrent rate was 28.8 % (21 / 73). The overall 5-year survival rates was 86.4 %. Multivariate analysis revealed that distant metastasis, age ≥ 45 years and primary T₄ were independent prognostic factors.

  Conclusion  A routine central compartmental neck dissection for medullary thyroid carcinoma is recommended, which includes removing the lymph nodes of superior mediastinum. Lateral neck compartmental dissection should be considered when lymph node metastasis is proved in ipsilateral central compartment intraoperatively. Total thyroidectomy, central and bilateral functional neck dissections should be considered in T4 patients.