Robotic thyroidectomy is an emerging technique with postoperative outcomes that are at least comparable to those of conventional endoscopic thyroidectomy, with some end-points appearing superior. Our multicenter series represents the largest comparison of robotic and endoscopic thyroidectomy to date, with results suggesting a comparable robot technology we used that could overcome some of the technical limitations associated with conventional endoscopic procedures, with reduced operation times and increased lymph node retrieval. Moreover, we found that the learning curve for robotic thyroidectomy was shorter than that for endoscopic thyroidectomy.
Endoscopic surgical techniques for thyroid cancer surgery can benefit patients by eliminating the anterior neck incision utilized in the traditional open approach. In addition to superior cosmetic results, endoscopic thyroidectomy can reduce postoperative pain and discomfort, shorten hospital stay, and enhance postoperative recovery [
The recent introduction of the da Vinci robot surgical system may be a major improvement in extracervical approaches for thyroid surgery and may be more ergonomic for surgeons than the endoscopic approach [
At present, endoscopic techniques are regarded as too time consuming and technically demanding to be adopted on a large-scale. The learning curve for endoscopic thyroidectomy performed by skilled endocrine surgeons has been estimated to be approximately 60 patients [
At present, the benefits of robotic thyroidectomy relative to endoscopic thyroidectomy, as determined by oncologic and functional outcomes, have not been fully clarified. Moreover, there have been no multicenter studies comparing learning curves for these two methods. We therefore compared the operative outcomes and surgical learning curves of robotic and endoscopic thyroidectomy in patients with differentiated thyroid carcinoma (DTC).
This comparative, multicenter study evaluated patients who underwent robotic or endoscopic thyroidectomy at three large-volume centers with considerable experience in thyroid cancer surgery. Clinical and pathological data were collected retrospectively at each institution and entered into a dedicated database for analysis. Between November 2001 and June 2010, 2,612 patients with DTC underwent thyroidectomies at three centers, with all operations performed by four surgeons. Of these patients, 1796 underwent robotic thyroidectomy and 843 underwent conventional endoscopic thyroidectomy. At the time of surgery there was no intention to compare the two procedures. This study was approved by the institutional review boards (IRBs).
At all institutions, perioperative workup included physical examination, high-resolution ultrasonography (US), and neck computed tomography (CT) and/or neck magnetic resonance imaging (MRI); preoperative staging US and neck CT (or MRI) was utilized to evaluate the degree of tumor invasion, including tumor size, extrathyroidal invasion, tumor infiltration of adjacent structures, and nodal involvement. Sonographic findings, such as loss of an echogenic thyroid capsule at the contact site of the primary tumor or contact with an adjacent thyroid capsule along more than 25% of the boundary of a tumor, were considered indicative of extrathyroidal extension [
In accordance with American Thyroid association (ATA) guidelines, a less than total thyroidectomy was performed in patients <45 years old, with a single lesion <1 cm in size, no definitive evidence of extrathyroidal invasion or lymph node metastasis, no personal history of radiation therapy to the head or neck, and no first-degree family history of DTC [
Clinical parameters analyzed included patient characteristics, operative variables, extent of surgery, pathologic findings, and short-term operative outcomes. Pathologic examinations included assessments of disease tumor-node-metastasis (TNM) stage, number of lymph nodes harvested, and number of metastatic lymph nodes. We also assessed perioperative complications, including hematoma, seroma, vocal cord palsy, hypocalcemia, trachea injury, esophageal injury, chyle leakage, and brachial plexus neuropraxia. All patients were followed up in the same manner at the three centers, including clinical examinations within 1 week of discharge and a 3-to-6-month follow up that included a physical examination, neck US, assay of tumor markers (serum thyroglobulin concentration), and/or a 131radioactive iodine (131RAI) scan.
To evaluate the learning curve for robotic versus endoscopic thyroidectomy, we used a protocol similar to those previously described for the evaluation of learning curves for thyroid surgery [
Data were analyzed using SPSS 12.0 for Windows (SPSS Inc., Chicago, IL, USA). All data are expressed as means ± standard deviations (SDs), proportions, or absolute numbers. Continuous data were compared using Student’s
A moving average method was used to analyze operation time and learning curves. Creating an average that “moves” with the addition of new data results in “smoothing” of the process being analyzed, thus reducing the effects of fluctuations. We used a moving average of 20 to reduce variations and accentuate trends [
Table
Demographics and extent of surgery in patients with thyroid carcinoma treated by robotic thyroidectomy versus endoscopic thyroidectomy.
Robot group ( |
Endoscopy group ( |
|
|
---|---|---|---|
Age, mean (years), range | 39.4 ± 9.1 (13–70) | 37.5 ± 9.4 (6–50) | NS* |
Gender | |||
Female | 1637 (92.5%) | 824 (97.7%) | NS |
Male | 132 (7.5%) | 19 (2.3%) | |
Extent of surgery | |||
Less than total | 1063 (60.1%) | 693 (82.2%) | 0.004 |
Unilateral total | 595 (33.6%) | 307 (36.4%) | |
Unilateral total + partial | 177 (10.0%) | 208 (24.7%) | |
Unilateral total + subtotal | 291 (16.4%) | 178 (21.1%) | |
Total | 706 (39.9%) | 150 (17.8%) | |
Extent of neck node dissection | |||
No dissection | 23 (1.3%) | 59 (7.0%) | <0.001 |
CCND** | 1675 (94.7%) | 770 (91.3%) | NS |
Selective node dissection | 11 (0.6%) | 0 (0%) | NS |
MRND§ | 60 (3.4%) | 14 (1.7%) | <0.001 |
NS*: nonspecific finding, CCND**: central compartment neck dissection, MRND§: modified radical neck dissection.
Pathologic results are shown in Table
Comparison of pathologic findings between patients treated with robotic thyroidectomy and endoscopic thyroidectomy.
Robot group ( |
Endoscopy group ( |
|
|
---|---|---|---|
Pathology | NS | ||
Papillary carcinoma | 1758 (99.3%) | 837 (99.3%) | |
Follicular carcinoma | 5 (0.3%) | 6 (0.7%) | |
Medullary carcinoma | 5 (0.3%) | ||
Hurthle cell carcinoma | 1 (0.1%) | ||
Tumor size, mean (cm) | 0.5 ± 0.5 | 0.4 ± 0.5 | NS |
Multifocality | NS | ||
Yes | 469 (26.5) | 110 (13.0%) | |
No | 1300 (73.5) | 733 (87.0%) | |
Bilaterality | NS | ||
Yes | 208 (11.8%) | 72 (8.5%) | |
No | 1561 (88.2%) | 771 (91.5%) | |
Mean retrieved central LN ( |
4.5 ± 2.6 | 2.9 ± 1.7 | <0.001 |
Mean metastatic central LN ( |
1.2 ± 0.9 | 1.0 ± 0.7 | NS |
TNM stage | |||
T1 | 905 (51.2%) | 513 (60.9%) | 0.011 |
T2 | 16 (0.9%) | 15 (1.8%) | |
T3 | 841 (47.5%) | 314 (37.2%) | |
T4a | 7 (0.4%) | 1 (0.1%) | |
N0 | 1131 (64.0%) | 605 (71.7%) | 0.001 |
N1a | 570 (32.2%) | 224 (26.6%) | |
N1b | 68 (3.8%) | 14 (1.7%) | |
Stage | 0.002 | ||
Stage I | 1480 (83.7%) | 750 (89.0%) | |
Stage II | 275 (15.5%) | 92 (10.9%) | |
Stage IVa | 14 (0.8%) | 1 (0.1%) |
LN: lymph node.
TNM: tumor-node-metastasis.
Total operation time for subtotal thyroidectomy was similar in the two groups, but was significantly shorter in the robotic than in the endoscopic group for total thyroidectomy (
Comparison of perioperative outcomes between patients treated with robotic thyroidectomy and endoscopic thyroidectomy.
Robot group ( |
Endoscopy group ( |
|
|
---|---|---|---|
Total operation time (min), range | |||
|
149.2 ± 32.3 | 172.7 ± 66.7 | <0.001 |
|
122.3 ± 32.4 | 127.2 ± 41.3 | NS |
Postoperative hospital stay (days) | 3.3 ± 1.3 | 3.4 ± 1.1 | NS |
Postoperative complications ( |
|||
Transient hypocalcemia | 276/706 (39.1%) | 55/150 (36.7%) | NS |
Permanent hypocalcemia | 0 (0%) | 2 (0.2%) | |
Transient hoarseness | 68 (3.8%) | 41 (4.9%) | |
Permanent hoarseness | 8 (0.5%) | 1 (0.1%) | |
Flap hematoma | 10 (0.6%) | 8 (0.9%) | |
|
8 (0.5%) | 5 (0.6%) | |
|
2 (0.1%) | 3 (0.4%) | |
Seroma | 40 (2.3%) | 19 (0.3%) | |
Tracheal injury | 3 (0.2%) | 4 (0.5%) | |
Esophageal injury | 0 (0%) | 0 (0%) | |
Transient chyle leakage | 6 (0.3%) | 3 (0.4%) | |
Transient traction injury | 3 (0.2%) | 1 (0.1%) | |
|
Of the 856 patients who underwent bilateral total thyroidectomy, 481 underwent 131RAI ablation (range, 30–150 mCi) and a 131RAI scan 5–7 days after 131RAI ablation. The remaining 375 patients did not undergo 131RAI ablation as they were deemed low risk (356 patients) or chose not to undergo such treatment (19 patients). No patient showed abnormal uptake on 131I whole body scans. At the time of 131RAI ablation (TSH stimulated), mean serum thyroglobulin levels were checked, serum thyroglobulin in 362 (75.2%) was <1 ng/mL and in the remaining 119 (24.8%) was >1 ng/mL (
When we compared the data on about 100 individual patients who underwent robotic and endoscopic less than total thyroidectomy by all involved surgeons, we observed no significant differences in patient-selection criteria. For both procedures, the operation times gradually decreased with accumulating experience. For all 4 surgeons, operation times reached a plateau after 35–45 robotic and 55–70 endoscopic less than total thyroidectomies (Figure
(a–d) Individual learning curves for robotic thyroidectomy (RT) and endoscopic thyroidectomy (ET); The graph plots the time taken to perform each procedure as a function of the number of patients. The moving average method was used to determine changes in operation times for each surgeon. The time required for each surgeon to perform RT decreased after 35–50 patients, whereas the time required by each to perform ET decreased after 55–70 patients.
Robotic thyroidectomy is an emerging technique with early outcomes that are at least comparable to those of conventional endoscopic thyroidectomy, with some end points appearing superior. Our series represents the largest comparison of robotic and endoscopic thyroidectomy to date, with results suggesting comparable operation times, perioperative outcomes, and complications. In addition, early-term oncologic outcomes demonstrated that robotic thyroidectomy resulted in acceptably complete resection and radical dissection, with an extremely low rate of recurrent disease at follow up. Moreover, to our knowledge, this study is the first multicenter trial to compare the learning curves of robotic and endoscopic thyroidectomy.
The goal of thyroidectomy plus neck dissection in patients with thyroid cancer is the complete surgical removal of the entire thyroid gland, along with radical cervical lymphadenectomy when necessary. Other goals include rapid convalescence and complete preservation of the recurrent and superior laryngeal nerves and the parathyroid gland. Only a few previous large series have compared perioperative outcomes in patients undergoing robotic and endoscopic thyroidectomy [
Endoscopic versus robotic thyroidectomy studies. Case series comparing perioperative outcomes.
Author, year | Study design | No. (patients) | Approach | Comparative parameters | Perioperative results | Complication rate | Oncologic safety (surgical completeness such as harvested lymph node) | Other notable findings |
---|---|---|---|---|---|---|---|---|
Lee et al. (2011) [ |
Prospective, controlled, single surgeon | RT* (163) versus ET§ (96) | GT** | Perioperative outcomes, |
Operation time |
No difference | Retrieved LN (RT > ET) | First comparative study between RT and ET. Showed superiority of RT in terms of operation time, lymph node retrieval, and learning curve |
| ||||||||
Lang and Chow (2011) [ |
Retrospective, controlled, single surgeon | RT (7) ET (39) | GT | Perioperative outcomes | Operation time |
No difference | No data | Described initial experience of RT in Hong Kong |
| ||||||||
Lee et al. (2011) [ |
Retrospective, controlled, single center | RT (580) |
GT | Perioperative outcomes | Operation time |
Transient- hypoparathyroidism |
Retrieved LN (RT > ET) | RT was found to be superior to ET in terms of operation time, and LN retrieval. |
| ||||||||
Kim et al. (2011) [ |
Retrospective, single center | RT (69) |
BABA§§ | Perioperative outcomes | Operation time |
No difference | Surgical completeness |
First comparative study of RT versus OT by analyzing postoperative outcomes |
RT*: robotic thyroidectomy, GT**: gasless transaxillary approach, ET§: endoscopic thyroidectomy, BABA§§: bilateral axillo-breast approach, OT#: open thyroidectomy.
A recent retrospective comparison of 580 patients who underwent robotic thyroidectomy and 570 who underwent conventional endoscopic thyroidectomy at a single center found that the operation time was shorter and the mean number of central LNs retrieved greater in the robotic than in the endoscopic group [
Objective comparisons are limited, however, by the lack of long-term surgical outcomes and by nonuniformity in defining, assessing, and reporting postoperative outcomes. Larger prospective studies, with uniform definitions of parameters, methodologies of data collection, and times of assessment are needed to compare operative outcomes of the two procedures.
The operation time required by a single surgeon to perform robotic thyroidectomy using a gasless transaxillary approach was found to reach a plateau after 40–45 operations [
Published data for surgical learning curves for robotic thyroidectomy.
Author, year | Study design | No. (patients) | Approach | Pathology | Operation | Operation time | Complications (Major)* | Methods for analysis | Surgical learning curve for robotic thyroidectomy |
---|---|---|---|---|---|---|---|---|---|
Kang et al. (2009) [ |
Retrospective |
338 | GT |
PTC§ (332) |
TT§§ & CCND# (104) |
Total: 144.0 ± 43.5 |
5/338 (1.5%) | Moving average | RT## (Console time): 40–45 cases |
| |||||||||
Lee et al. (2011) [ |
Retrospective |
163 | GT | PTC (151) |
TT (48), LTT (115) |
Total: 110.1 ± 50.7 |
2/163 (1.2%) | Moving average | RT: 35-40 cases, |
| |||||||||
Lee et al. (2011) |
Prospective |
644 | GT | PTC (616) |
TT & CCND (353) |
Total: 181.5 ± 78.2 |
2/644 (0.3%) | Comparative analysis between beginners and experience surgeons | RT (LTT): 40 cases |
| |||||||||
Kandil et al. (2012) [ |
Prospective |
100 | GT | No data | TT (22) |
Total: 121.9 ± 63.8 |
1/100 (1.0%) | Comparative analysis between early experience and late experience | RT: 45 cases |
Complications (Major)*: major complications mean permanent damages such as recurrent laryngeal nerve injury, permanent hypocalcemia, hematoma of muscle flap need to reoperation, hemorrhage of a major vessel need to reoperation, trachea injury, Honor’s syndrome, major chyle leakage, and brachial plexus neuropraxia (not including minor complications such as transient hypocalcemia, transient hoarseness, wound seroma, wound infection, and hematoma of muscle flap only need to conservative management), GT**: gasless transaxillary approach, PTC§: papillary thyroid carcinoma, TT§§: total thyroidectomy, CCND#: central compartment node dissection, RT##: robotic thyroidectomy, LTT
This study had potential shortcomings. First, although all 4 surgeons in our study used the same technique, all procedures could not be completed with the same quality of manipulations. Second, patients were not randomized, as it was neither ethically nor geographically possible to move patients from one center to another. This was likely a result of selection bias of our patients and our overall experience with endoscopic and robotic surgery. Third, the short history of robotic thyroidectomy makes assertions on the oncologic safety and the surgical learning curve premature. In addition, the surgeon had experience in performing several endoscopic thyroidectomies prior to any robotic thyroidectomies, and this is likely to have influenced comparisons of operation times and learning curves. Therefore, further study is required to confirm these findings and to assess the surgical learning curve for surgeons who have no experience of endoscopic surgery. Moreover, a prospective and randomized study with longer follow-up period should be conducted to evaluate the role of robotic surgery in thyroid disease.
In conclusion, we have shown that the robot technology we used could overcome some of the technical limitations associated with conventional endoscopic procedures, with reduced operation times and increased lymph node retrieval. Moreover, we found that the learning curve for robotic thyroidectomy was shorter than that for endoscopic thyroidectomy. Prospective randomized studies are required to evaluate the actual learning curves of inexperienced endoscopic surgeons for robotic thyroidectomy and lymph node dissection.
All authors including Drs. J. Lee, J. H. Yun, U. J. Choi, S.-W. Kang, J. J. Jeong, and W. Y. Chung have no conflict of interests or financial ties to disclose.