With advancements in endoscopic technology and surgical instruments, endoscopic thyroidectomy has emerged as a safe surgical approach for patients with PTC [13]. Endoscopic thyroidectomy techniques aim at reaching efficacy and safety with fewer perioperative adverse events and better cosmetic outcomes [14]. In our previous study, we demonstrated the feasibility of this technique in the treatment of papillary thyroid non-microcarcinoma (PTNMC) [15, 16]. However, most of the previous trials and our prior studies were limited by a short-term follow-up period for patients with disease-free status [17–19]. In the present study, we conducted a long-term institutional follow-up after surgery (average of 10 years) to more accurately estimate recurrence or metastasis rates.
Long-term follow-up is critical to the evaluation of relapse-free survival (RFS) and disease-free survival (DFS) [20, 21]. During the average 10 years of follow-up, recurrence/metastasis was found in four patients in our present study. Two patients were diagnosed with new lesions in the contralateral thyroid lobe, which were confirmed as PTC by FNA and treated with a second open surgery. The other two patients were found to have lymph node metastasis in the lateral cervical region by cervical B ultrasound, also diagnosed as PTC by FNA, and underwent a second open lateral neck dissection. No residual lesion was found in the thyroid or central neck area during the long-term follow-up, indicating that endoscopic surgery is an effective method for thyroidectomy and central neck dissection. Furthermore, there was no statistically significant difference in recurrence/metastasis between the en bloc and conventional group, suggesting that en bloc is a viable alternative method implemented in endoscopic thyroidectomy.
En bloc resection is an appropriate approach for oncologic concept [8], and it has been utilized in thyroid surgery at our institute since January 2010 [22]. In our current study, we observed a significant increase in the number of lymph node obtained in the modified en bloc group (7.5 ± 4.5) compared to the conventional group (5.6 ± 3.6) (P < 0.01). Moreover, the incidence of lymph node metastasis was significantly higher in the modified en bloc group (50/108, 46.3%) than in the conventional group (70/213, 32.9%) (P = 0.02). There was no significance difference in the comparison of recurrence/metastasis rate between the modified en bloc group and conventional group. These findings indicate that en bloc resection is an effective method for central neck dissection during endoscopic thyroidectomy.
Preserving the inferior parathyroid gland can be challenging, especially when it is located between paratracheal lymph nodes during endoscopic thyroidectomy, leading to a controversial issue [23]. In this study, we introduced the en bloc dissection method in endoscopic thyroid surgery to determine whether it increases the difficulty of preserving the parathyroid gland and its blood vessels. Our results showed that the incidence of parathyroid tissue resected and requiring intramuscular injection (parathyroid transplant) was similar in both the modified en bloc group (22.2%, 24/108) and the conventional group (19.2%, 41/213) (P = 0.53). Furthermore, there was no significant difference in the rate of transient hypocalcemia between the modified en bloc group (3/108, 2.8%) and the conventional group (4/213, 1.9%). Therefore, our findings suggest that en bloc resection in endoscopic thyroid surgery does not increase the incidence of parathyroid gland injury.
We compared the postoperative complications of en bloc resection with the conventional method in endoscopic thyroid surgery. Our study showed no significant difference in the incidence of transient or permanent vocal cord paralysis or hypocalcemia between the two groups. Additionally, none of the cases in our study experienced surgical complications such as recurrence around subcutaneous tunnel, subcutaneous emphysema, tracheal injury, or Horner’s syndrome. Furthermore, no cases required conversion to open surgery due to uncontrollable bleeding or other reasons. Based on these results, en bloc resection appears to have similar surgical complications compared to the conventional method and can be considered as a safe procedure.
En bloc resection via BAA in endoscopic thyroid surgery requires a learning curve as it is a new operating method. The learning curve was reflected by the following criteria: A) operative time, B) blood loss, and C) number of harvested lymph nodes [24]. In the present study, a surgeon with less experience in en bloc resection completed the learning curve after performing 35 operations and demonstrated a decrease in surgical time with increased consistency. The result was similar with other surgical centers. Dabsha, et al reported the statistical significance in learning curve development of endoscopic thyroidectomy via trans-oral and trans-axillary approaches were noticed ranging between 6 and 15 annual cases [25]. Kandil, et al reported that, compared to trans-axillary endoscopic thyroidectomy, which required a learning curve of 69 cases, BAA appears to be easier to learn [26]. Moreover, the other technical indexes, including operative duration, blood loss, and postoperative hospital stay, were quite similar between the en bloc and conventional groups. Based on our findings, en bloc resection can be considered a feasible procedure in endoscopic thyroidectomy.
Quality of Life (QOL) is a major concern, especially after thyroid surgeries [27]. The scar in the neck can cause patients significant psychological burden, and the history of minimally invasive thyroid surgery has been associated with better thyroid cancer specific QOL [3]. The cosmetic result of BAA, which leaves no visible scar in the neck, was found to be excellent, and the scars in the mammary areolas were almost invisible one month postoperatively (see Fig. 3). Furthermore, preliminary studies have shown that patients who underwent BAA reported lower scores of scar self-consciousness, higher cosmetic satisfaction, and QOL compared to those who underwent open surgeries (data not shown in this study). These findings suggest that endoscopic thyroid surgery via BAA may be a relatively effective procedure in improving QOL after thyroid surgeries.
The current study has some limitations that should be considered when interpreting the results. Firstly, it was a retrospective study conducted in a single institution, which may limit its generalizability to other settings. Secondly, the resection range of thyroidectomy and prophylactic CND was based on Chinese national guidelines for the treatment of thyroid cancer [28], which may be more suitable for the Asian population. To overcome these limitations and for a more precise analysis, well-designed, prospective, multicenter, and randomized controlled clinical trials should be conducted in the future. However, despite these limitations, our present study enrolled a large sample of patients who underwent endoscopic thyroid surgery via BAA. Moreover, patients in this study were followed up for a long-term (average 10 years) to assess the effectiveness of the en bolc and BAA methods.
In conclusion, our results demonstrate that en bloc resection in endoscopic thyroid surgery via BAA is a technically feasible, safe, and effective procedure with excellent cosmetic results. This approach can be considered as a viable surgical option for selected patients with PTC who are preoperatively diagnosed with a dominant diameter of ≤ 2cm and without metastasis, and who are concerned about cosmesis. However, further prospective, multicenter, and randomized controlled trials are needed to validate these findings and establish the long-term efficacy and safety of this approach.