The learning curve of endoscopic thyroid surgery for papillary thyroid microcarcinoma: CUSUM analysis of a single surgeon’s experience

BACKGROUND: With the development of surgical technics, endoscopic thyroid surgery has been gradually accepted and utilized in thyroid disease treatment, including thyroid carcinoma. This study aimed to evaluate the learning curve for endoscopic hemithyroidectomy (EHT) with ipsilateral central neck dissection (CND) and investigate how many cases must be performed before a surgeon becomes competent and proficient in this approach. METHODS: Ninety-nine consecutive patients who underwent EHT with ipsilateral CND for papillary thyroid microcarcinoma by a single surgeon between June 2015 and October 2017 were analyzed. Multidimensional cumulative summation (CUSUM) analysis was performed to evaluate the learning curve. RESULTS: The CUSUM graph showed the learning curve ascended in the first 31 cases and declined in the following cases. The number of lymph nodes removed in phase 2 (the following 68 cases) was significantly more than that in phase 1 (the first 31 cases) (5.06 ± 1.44 vs. 4.19 ± 1.51, P = 0.001). The operation time in phase 2 was shorter than that in phase 1 (123.38 ± 12.71 min vs. 132.90 ± 13.95 min, P = 0.008) and the rate of accidental removal of parathyroid gland decreased from 35.5% in phase 1 to 16.2% in phase 2 (P = 0.040). There was a declining trend but no significant difference in the rate of postoperative complications (9.7% in phase 2 vs. 4.4% in phase 1, P = 0.309). CONCLUSION: EHT with ipsilateral CND performed by surgeons was mastered after 31 cases, and the safety and feasibility of this endoscopic approach can also be demonstrated.