Novel methods in thyroid surgery
Since the first report of endoscopic thyroid lobectomy in 1997, various endoscopic thyroid techniques or approaches have been described. Many studies have reported several advantages of endoscopic thyroidectomy (ET) compared with open thyroidectomy, including better cosmetic results, a lower rate of post-operative complications, and better completion rate for surgery. However, ET remains a technically challenging procedure. The two-dimensional visual representation and use of nonflexible endoscopic instruments can make it difficult to visualize the surgical field adequately and to manipulate instruments.
The Da Vinci robotic system was developed to improve the weak points of endoscopic surgery, and surgical robots have been successfully applied to a number of disciplines. Recent studies have reported that robotic thyroidectomy (RT) is a feasible, safe, and effective method of performing such surgeries, although most studies have been limited by small samples size and assessment at a single institution. In this study, we aimed to determine the relative merits of RT and ET by performing a meta-analysis of studies comparing the two techniques.
A literature review of comparative studies
Study 1
A study published in 2012 investigated 165 patients undergoing endoscopic thyroidectomy (endoscopy group) and 46 patients undergoing robotic thyroidectomy (robot group). A gasless transaxillary approach was used in both groups. They found that both patient groups were similar in terms of patient characteristics, mean number of retrieved central lymph nodes, pathological features, length of hospital stays, postoperative complication rate, and serum Tg level. However, the mean total operation time for thyroidectomy was significantly less in the endoscopy group. Postoperative total drainage for lobectomy was also lower for the endoscopy group. Cost effectiveness is also an important consideration when evidence for predominance of two surgical techniques is lacking. The mean cost of robotic thyroidectomy was approximately 8 times that of endoscopic thyroidectomy. There was no significant difference in postoperative complications as hypocalcemia, recurrent laryngeal nerve injury, chyle leakage and tracheal injury in the two groups. Therefore, in this study robotic thyroidectomy was lengthier in duration than endoscopic thyroidectomy, more costly, and associated with increased postoperative drainage with no improvement in oncologic outcomes or complication rates. Therefore this report does not support any advantage of robotic surgery over endoscopic surgery.
Study 2
Another study published in 2012 compared the potential advantages of robotic versus endoscopic thyroidectomy. They analyzed 218 consecutive patients who underwent endoscopic (105 cases) or robotic (113 cases) thyroidectomy using a gasless unilateral axillo-breast or gasless unilateral axillary approach. They reported that because of the dexterity of robotic instruments and the improved surgical view, it was subjectively easier and took less time to perform a complete total thyroidectomy and central compartment neck dissection in robotic thyroidectomy. In the case of unilateral lobectomy, endoscopic and robotic thyroidectomy had quite similar surgical outcomes. Cosmetic satisfaction was excellent in both groups. In this pool of surgeries performed by a single surgeon, robotic thyroidectomy was superior to endoscopic thyroidectomy for performing total thyroidectomy and bilateral central compartment neck dissection. However, in terms of cost-effectiveness, endoscopic thyroidectomy was comparable to robotic thyroidectomy in patients who undergo unilateral lobectomy.
Study 3
In this study published in 2011 the aim was to confirm the merits of robotic thyroid surgery by comparing the surgical outcomes of robotic-assisted and conventional endoscopic thyroidectomy in papillary thyroid microcarcinoma (PTMC) patients. From November 2001 to July 2009, 1150 patients with PTMC underwent endoscopic thyroidectomy using a gasless, trans-axillary approach. Of these patients, 580 underwent a robotic procedure (the robotic group; RG) and 570 a conventional endoscopic procedure (the conventional endoscopic group; EG). These 2 groups were retrospectively compared in terms of their clinicopathologic characteristics, early surgical outcomes, and surgical completeness. Total thyroidectomy was performed more frequently in the RG. They found that although mean operation times were not statistically different, the mean number of central nodes retrieved was greater in the RG than in the EG. Mean tumor size were not significantly different in the 2 groups, but the RG showed more frequent central node metastasis and capsular invasion. Tumor and nodal statuses in the RG were more advanced than in the EG. Regarding postoperative complications, transient hypocalcemia was more frequent in the RG, but other complication frequencies were not significantly different in the 2 groups. Postoperative serum thyroglobulin levels were similar in 2 groups, and short-term follow-up (1 year) revealed no recurrence by sonography and no abnormal uptake during radioactive iodine therapy in either group. They concluded that the application of robotic technology to endoscopic thyroidectomy could overcome the limitations of conventional endoscopic surgery during the surgical management of PTMC.
Study 4
In another study published in 2011, between April 2007 and March 2010, 96 patients underwent endoscopic thyroidectomy (endoscopy group) and 163 patients underwent robotic thyroidectomy (robot group). A gasless transaxillary approach was used in both groups. The 2 groups were compared in terms of patient characteristics, perioperative clinical results, complications, and pathologic details. Learning curves for the 2 procedures were compared based on the number of cases required to reach a consistent operation time. They found that patient characteristics were similar for both groups. The mean total operation time for thyroidectomy with central compartment neck dissection was 142.7 ± 52.1 min in the endoscopy group and 110.1 ± 50.7 min in the robot group (P = .041). Both patient groups were similar in terms of pathological features including TNM stage, intraoperative blood loss, length of hospital stay, and complication rate. However, the mean number of retrieved central lymph nodes was 2.4 ± 1.9 for the endoscopy group and 4.5 ± 1.5 for the robot group (P = .004). The learning curve was 55-60 cases for endoscopic thyroidectomy and 35-40 cases for robotic thyroidectomy. They concluded that robotic thyroidectomy was found to be superior to endoscopic thyroidectomy in terms of operation time, lymph node retrieval, and learning curve. Complication rates and postoperative hospital stay were similar for the 2 procedures.
Study 5
Another study published in 2011 posed that gasless, transaxillary endoscopic thyroidectomy (GTET) offers a distinct advantage over the conventional open operation by leaving no visible neck scar, and in an attempt to improve its ergonomics and surgical outcomes, the robotically assisted thyroidectomy (RAT) was introduced. The RAT uses the same endoscopic route as the GTET but with the assistance of the da Vinci S robotic system. Excellent results for RAT have been reported, but it remains unclear whether RAT offers any potential benefits over GTET. From June to December 2009, they investigated 46 patients underwent endoscopic thyroidectomy. Of these patients, 39 had surgery without the robot (GTET) and 7 had surgery with the robot (RAT). Demographics, surgical indications, operative findings, and postoperative outcomes were compared between the two groups. All the patients were followed up for at least 6 months after surgery. They found that patient demographics, surgical indications, and extent of resection were similar between the two groups. The median total procedure time was significantly longer for RAT than for GTET, but the contralateral recurrent laryngeal nerve was more likely to identify in RAT (100%) than in GTET (42.9%). On the average, GTET needed one more surgical assistant than RAT. The median pain score on postoperative day 0 was significantly higher with RAT than with GTET but was similar on day 1. Blood loss, hospital stay, and surgical complications were similar in the two groups. They concluded that adding the da Vinci S robot to GTET increased the total procedure time and resulted in a higher pain score on day 0 but eliminated the need for any surgical assistant at the time of the operation.
Study 6
And final study also published in 2011 evaluated 302 patients undergoing total thyroidectomies and central lymph node dissection (CND) with cancer less than 1 cm. Patients were divided into three groups according to operation methods (open group; n = 138), (endo group; n = 95), (robot group; n = 69). They reported that young patients preferred the robotic and endoscopic surgery. The number of retrieved lymph nodes in the robot group was not different from the endo group. The operative time of the robot group was longer than the endo group. The total drain amount in the robot group was more than the endo groups; however, there was no difference in the length of hospitalization and complication rates. They also found that endo group showed higher postoperative serum thyroglobulin off thyroid hormone (Off-Tg) when compared to the open and robot groups. They concluded that robotic surgery was equal to open surgery except with respect to operative time and was superior to endoscopic surgery in Off-Tg levels presenting completeness of the operation in thyroid cancer surgery. Because it has excellent cosmetic results and various technical advantages, it should be considered in young, low-risk patients with thyroid carcinoma less than 1 cm
Meta-analysis and Discussion
A new article published in 2012 conducted a meta-analysis to determine the relative merits of robotic thyroidectomy (RT) and endoscopic thyroidectomy (ET). The performed extensive literatures search to identify comparative studies reporting peri-operative outcomes for RT and ET. Among the pool of studies with this focus, the six abovementioned studies matched the selection criteria, which reported on 2048 subjects, of whom 978 underwent RTand 1070 underwent ET. Comparing the outcomes of RT with ET, this meta-analysis indicated that RT was associated with more complications and greater amount of drainage fluid. Meanwhile, operating time, conversion, post-operative hospital stay and the number of lymph nodes harvested were similar for both procedures.
According to them, RT is often perceived as being more time-consuming, because of the additional set-up time required [20]. Operating times depend mainly on the experience and skill of the surgeon. In this meta-analysis, the authors found that there was no significant difference in operating time between RT and ET. This may be attributable to the shortened learning curve with RT, as it has been suggested that robotic systems make the technique easier to learn, even by relatively inexperienced endoscopic surgeons. With increasing experience, set-up time gradually decreased, and the actual time may be shorter in RT. There was no significant difference in conversion rates between RT and ET. Although RT offers a number of advantages over ET, including improvements in manual dexterity, ergonomics, and visualization, the results of this meta-analysis suggest that there is no additional clinical benefit for RT over ET. The disadvantages of RT are a higher rate of complications and a greater amount of drainage fluid. It has been suggested that the characteristics of RT might reduce complications because, using the Da Vinci Surgical System, robotic arms are used for retraction and dissection, and their use has been found to reduce unnecessary procedures and to minimize iatrogenic tissue injury during retraction. Consequently, the results of this meta-analysis difficult to explain, and more studies are needed before such a conclusion can be drawn. There was no difference in post-operative hospital stay between the two groups, implying that the time required for patients to resume daily activities might be similar between RT and ET.
Oncologic outcomes after thyroid cancer surgery are affected by the extent of lymph-node dissection and the completeness of thyroidectomy. Some studies have concluded that more lymph nodes are harvested via RT compared with ET, and that the robotic method may improve the long-term prognosis in patients who undergo surgery for thyroid cancer. In this meta-analysis, the authors found no significant differences between RT and ET in the number of lymph nodes harvested; however, they suggested that long-term follow-up evaluation would be necessary to evaluate the exact oncologic outcomes of RT for thyroid cancer.
They concluded that the results of their meta-analysis indicated that RT is associated with an increased risk of complications and a greater amount of drainage fluid. Therefore, RT does not appear to have any advantage over ET. According to them, further studies are required to confirm these results.
