Ojectives: The extent of thyroid surgery for unilateral sporadic medullary thyroid carcinoma (sMTC) still remains controversial. Therefore, the purpose of this study was to evaluate the treatment outcomes of hemithyroidectomy for sMTC at Kyoto University Hospital.

Methods: All patients who underwent curative hemithyroidectomy for sMTC at Kyoto University Hospital between August 2003 and August 2020 were included in this study. The clinical course of patients were retrospectively reviewed.

Results: A total of 9 patients who met the inclusion criteria were enrolled. There were 4 males and 5 females, with a mean age of 66 years (IQR: 62-75). The median follow-up period was 9.05 years (IQR: 7.60-11.05). One patient underwent hemithyroidectomy with lateral neck dissection, and 8 patients underwent hemithyroidectomy with central neck dissection. One patient who underwent lateral neck dissection demonstrated mediastinal recurrence; however, this recurrence case was successfully salvaged through reoperation. In contrast, all patients who received central neck dissection remained recurrence-free during the follow-up period. The 5-year overall survival (OS) rate was 89%, and the 5-year disease-specific survival (DSS) rate was 100%.

Conclusion: For patients with unilateral sMTC, hemithyroidectomy with central neck dissection may be adequate as a locally curative surgery.