Approaches to single port mediastinal surgery

Introduction

No development in thoracic surgery in the last 40 years has had as profound an impact as the advent of video-assisted thoracic surgery (VATS).^1–3 The benefits of minimizing surgical access trauma for chest operations have revolutionized practices, not only in reducing patient morbidity but also in expanding the reach of curative surgery to patient categories and pathological indications previously deemed “unresectable.”^1–3 The vast majority of clinical experience and scientific publications on VATS has focused on pulmonary surgery. In particular, the accumulation of clinical evidence since the 1990s showing its clear superiority over open thoracotomy has enabled VATS to become accepted today as the preferred surgical approach for early stage lung cancer surgery.^3–5

The logical consequence of this was that surgeons sought to minimize surgical trauma even further by reducing the size and number of surgical access incision. This has culminated in the emergence of Uniportal VATS (UVATS), employing only one surgical port for initially simple procedures such as lung wedge resections and pneumothorax surgery,^6,7 and then later for lobectomy and ever more complex pulmonary operations . When compared to conventional multiportal VATS for treatment of early-stage lung cancer, there is now a considerable body of accumulated clinical evidence to suggest that UVATS delivers: equivalent safety; equal or better patient outcomes (especially in reduced pain); and equivalent treatment efficacy.^2,8,9

Given the increasing adoption of UVATS for lung surgery worldwide,^10,11 it is reasonable to project that a single-port approach for minimally invasive surgery for the mediastinum should also be explored. Surprisingly, the very first “single-port” approach for mediastinal surgery may be traced back to the 1960s, with the introduction of the transcervical approach for thymectomy. ¹² This approach was championed by a handful of prominent surgeons such as Joel Cooper, and published reports demonstrated good patient outcomes. ¹³ However, lingering questions remained over the adequacy of lower thymus clearance, and over time the transcervical approach failed to match the burgeoning popularity of VATS for thymic operations. ¹⁴

Other than the transcervical approach, development of single-port mediastinal surgery has lagged well behind UVATS pulmonary resection until relatively recently. This narrative (not systematic) review aims to provide an overview of the emergence of single-port mediastinal surgery.

Intercostal single port approach

The reemergence of interest in single port mediastinal surgery was ignited soon alongside early experimentation with UVATS for simple lung procedures.^6,7 A book chapter on Diagnostic VATS from 20 years ago described a technique of coaxial employment of a biopsy forceps along the video-thoracoscope in a single shared port was described for mediastinal and pleural biopsies. ¹⁵ A case series of 13 patients was subsequently published using two endoscopic instruments sharing a single port with the video-thoracoscope for biopsy of mediastinal lymph nodes, demonstrating the feasibility of the approach. ¹⁶

From there, UVATS via an intercostal approach was used for more complex resections, including of mediastinal tumors (Figure 1A). ¹⁷ A number of comparative studies have now been reported, contrasting UVATS with multiportal VATS for such operations. In 2015, a propensity score match study compared UVATS with multiport VATS for mediastinal tumor resection (29 patients in each arm). ¹⁸ This study found that UVATS gave significantly better results in terms of: operation duration; pain on postoperative day 1; pain on day of discharge; and length of hospital stay. A larger propensity score match study in 2018 compared UVATS with multiport VATS for mediastinal surgery (123 patients in each arm). ¹⁹ For both thymoma resection and for management of other mediastinal disease, this study demonstrated significantly better results with UVATS in terms of: operation duration; intraoperative blood loss; and postoperative pain scores. A 2019 propensity score match study compared UVATS with 2-port VATS for resection of mediastinal tumors (40 patients in each arm) and found UVATS gave better results in terms of: operation duration; and chest drain duration. ²⁰ Another 2019 study compared UVATS with 3-port VATS for resection of mediastinal cysts specifically, and found UVATS gave better results in terms of: operation duration; chest drain duration; and postoperative length of stay. ²¹ Finally, a 2022 propensity score match study from China compared UVATS with 2-port VATS for resection of thymic tumors (42 patients in each arm) and found UVATS gave better results in terms of: chest drain duration; postoperative length of stay; and postoperative pain scores. ²²

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Figure 1.

Schematic illustration of different approaches to single port mediastinal surgery (incision indicated by pink oval): (A) intercostal Uniportal VATS (UVATS) approach; (B) subxiphoid UVATS approach; (C) single-port intercostal robot-assisted thoracic surgery (RATS) approach with conventional multiarm robot surgery system; (D) single-port subxiphoid RATS approach with single-port RATS system (multiple arms via a single trocar).

Subxiphoid single port approach

One of the lessons from the development of VATS was that the key contributor to the pain and morbidity from thoracic surgery was pressure on the intercostal nerves causing neuropathy.^1,2 Even when this was reduced by transitioning from open thoracotomy to VATS, the paresthesia resulting from the neuropraxia was not completely eliminated.^23,24 As a result, interest developed to find a surgical approach that avoided intercostal neuropraxia altogether.

In 2012, Takeshi Suda first reported a technique of subxiphoid single port thymectomy. ²⁵ A port developed for single incision laparoscopic surgery was placed via a 3.5 cm subxiphoid incision, and this allowed for insertion of the video-thoracoscope, two long endoscopic curved instruments, and also carbon dioxide insufflation (Figure 1B). Suda's group later compared their initial experience using this technique in 46 patients with a historical group of 35 patients who received thymectomy via conventional multiportal intercostal VATS. ²⁶ They reported that their subxiphoid single-port technique gave better results in terms of: length of hospital stay; amount of postoperative analgesic use; and duration of postoperative analgesic use.

Subxiphoid UVATS has subsequently been used in a small number of centers around the worldwide for both pulmonary and mediastinal surgery. In 2018, the first book on subxiphoid VATS was published, and this already contained five chapters on subxiphoid VATS thymectomy authored by surgeons from four different thoracic surgery centers in Asia and Europe. ²⁷

In 2024, two centers in Shanghai reported their experience using subxiphoid UVATS for resection of thymic tumors. In the first, a propensity score match study compared a modified subxiphoid UVATS with median sternotomy for resection of T2-3 thymic malignancies (72 patients in each arm) and found the subxiphoid approach gave better results in terms of: operation times; intraoperative blood loss; chest drain duration; postoperative length of stay; and postoperative complication rates. ²⁸ Notably, this study also reported equivalent 5-year freedom from recurrence and 5-year overall survival rates. The second was a randomized controlled trial comparing subxiphoid VATS (n = 51) with intercostal VATS (n = 50) for suspected thymoma. ²⁹ This study found no difference between the surgical approaches with regards length of stay and amount of analgesics used, but reported that the subxiphoid group had lower pain scores during most of the postoperative stay.

Robot-assisted single port approaches

The other mega-trend in minimally invasive thoracic surgery over the last 25 years besides the rise of VATS and UVATS has been the more gradual but similarly significant adoption of robot-assisted thoracic surgery (RATS). ³⁰ Unsurprisingly, this has been used for mediastinal surgery. Takeshi Suda described a multiportal subxiphoid RATS approach for thymectomy, using a central subxiphoid camera port flanked by two subcostal ports on either side for the robot instrument arms. ³¹ In a 2016 report of his group's early experience, Suda compared eight cases performed using this RATS approach with 72 cases performed using his aforementioned subxiphoid UVATS approach. ³¹ It was reported that the multiportal subxiphoid RATS approach was associated with a shorter average operating duration, but there was no difference between the approaches in terms of hospital stay and duration of analgesic use.

The more common use of RATS for mediastinal surgery has remained via an intercostal approach.^30,32 In more recent years, the multiportal intercostal RATS strategy has been evolved by some investigators to become a single-port intercostal RATS technique, whereby the camera and instruments arms of a conventional multiportal robot surgery system are all inserted into the chest via a single incision (Figure 1C).^33,34 In a 2019 report of a South Korean group's initial experience, 14 cases of mediastinal mass resection performed using a single-port intercostal RATS approach was compared with 44 cases performed using an intercostal UVATS approach. ³³ The single-port intercostal RATS approach was associated with a shorter average length of hospital stay, but there was no difference between the approaches in terms of all other standard outcome measures.

A new generation of single-port RATS system has now emerged on the market. ³⁵ These have thinner multijointed wristed instruments and a fully wristed 3D high-definition camera, and are designed specifically to be inserted via a single trocar (Figure 1D). Use of such a single-port RATS system has now been reported for mediastinal surgery, with both an intercostal and a subxiphoid single-incision strategy being reported.^35,36 One group from South Korea reported a case series using the single-port RATS system via a subxiphoid or subcostal approach for thoracic surgery in 100 patients, including 41 thymectomies and 13 mediastinal mass excisions. ³⁶ No safety issues or conversions to open surgery were reported. In 2024, a multi-institutional propensity score match study compared thymectomy performed by the single-port RATS system via a subxiphoid approach versus the subxiphoid UVATS (25 patients in each study arm). ³⁷ Patient pain scores on the first postoperative day were lower in the single-port subxiphoid RATS group, but there was no significant difference at any of the other time points after surgery.

Evidence synthesis

Video-assisted thoracic surgery for early-stage lung cancer is now well-established as the surgical approach of choice for early stage lung cancer.^3–5 It achieved this recognized status through many years of accumulation of real-world clinical evidence. Crucially, this evidence compared VATS with the previous “gold standard” and demonstrated that VATS: (i) provided equal safety; (ii) yielded clinical advantages when measured by a range of clinical outcomes; and (iii) demonstrated equivalent (or better) treatment efficacy.^1–3 This stepwise accrual of clinical evidence constitutes a crucial model for the evaluation of any new surgical technique or innovation. ³⁸ Single-port approaches for mediastinal surgery are no exception.

With regards safety, one primary consideration is the volume of successful operations reported to have been performed without significant issues. For conventional VATS pulmonary resections, thousands of cases were reported during the 1990s to early 2000s.^1–3 For UVATS pulmonary resections, a 2019 systematic review identified 22 major case series which included 1926 lobectomies and 333 segmentectomies. ³⁹ The mortality rate for UVATS lung resection in 16 of the 17 individual studies reporting this statistic was 0%, and the remaining one study reported mortality in only 1 out of 30 segmentectomies (3.3%).^39,40 Such results established the safety of VATS and UVATS for pulmonary resections. In contrast, case series for single-port approaches for mediastinal surgery typical contain only dozens of patients, and the total reported cases worldwide for intercostal UVATS, subxiphoid UVATS, and single port RATS are still relatively small as noted above. ⁴¹ Furthermore, the majority of reports for each of these single-port techniques tend to come from only a handful of centers. Whether the safety reported for any one technique by a center specializing in it can be reproduced in other centers worldwide has thus far not been demonstrated. On the positive side, though, it is noted that until now no significant reports of harm attributable to any of these single-port approaches for mediastinal surgery have emerged.

With regards the demonstration of clinical advantages, the studies comparing single-port approaches for mediastinal surgery with other established approaches have tended to suggest better outcomes for single-port techniques in terms of some “crude” outcome measures (such as operation times, chest drain durations, lengths of stay, and postoperative pain). ³⁸ However, some important caveats apply when considering these findings:

With few exceptions, these studies are mostly retrospective in design and contain small cohorts. Even with propensity score matching, issues concerning reliability of analysis cannot be completely eliminated. The studies mostly come from the lowest levels of the “Pyramid of Evidence.” ⁴²

Given the above considerations, it is perhaps difficult to reach definitive conclusions about whether intercostal UVATS, subxiphoid UVATS, and single port RATS can actually confer better outcomes than other surgical approaches for mediastinal surgery. Moreover, the costs of any perceived improvements (including capital, consumable, training, and maintenance costs) have received virtually no attention. Hence it is also unknown what the potential value in adopting these new techniques may offer.

With regards treatment efficacy, such as measured by rates of R0 resection and survival, ³⁸ the vast majority of published papers on single-port mediastinal surgery have simply not reported these. As noted above, only one comparative study looking at subxiphoid UVATS reported rates of 5-year freedom from recurrence and 5-year overall survival. ²⁸ Overall, it remains impossible to fully ascertain if single-port mediastinal surgery may have compromised therapy in any way compared to more established surgical approaches.

In summary, the quantity and quality of evidence on this topic is still limited. ⁴¹ One can observe that the variations of single-port mediastinal surgery have been shown to be feasibly performed in some centers. Beyond this, it may still be premature to draw absolute conclusions about the safety, benefits and efficacy of the single-port approaches vis-à-vis more established techniques. It may be prudent to view these single-port approaches at present through the lens of clinical trialing, with a view toward accumulating more study data. Only when sufficient, good-quality evidence has been gathered should it be advisable to reconsider any role for them in mainstream surgical practice.

Future studies?

It is evident that future clinical studies will be essential to determine the place of single-port approaches for mediastinal surgery in thoracic practice. However, the track record of studies in this field over the past decade leaves much to be desired. Not only is their quantity and quality still short of ideal standards but they also show a potentially worrying feature. That is, surgeons appear to have a mercurial tendency to quickly experiment with any new idea or concept, with little hesitation before trying these on actual human patients.^41,43 Whereas the establishments of VATS and UVATS for pulmonary resection each took over a decade of gradual stepwise accumulation of data, we have witnessed the feverish leaps from UVATS mediastinal biopsy, to UVATS major mediastinal resection, to subxiphoid UVATS, and to the various modes of single port RATS in rapid succession with little time for review of evidence in-between. Each step appears to have been taken before the evidence for the previous one has even had time to mature. Indeed, when reading many of the papers quoted above, it does not escape notice that a number of them have not acknowledged that their experience was even in the form of a trial or that relevant Institutional Review Board approval was obtained.

On one hand, intrepid surgeons should always be encouraged to innovate and explore new methods of improving patient outcomes. However, this spirit of enterprise should be partnered with the surgical first principle of nonmaleficence.

In a 2018 commentary on subxiphoid VATS, this point regarding future studies in this field was stressed. ⁴¹ It was noted that in medical therapeutics, any new pharmaceutical treatment is rigorously subject to strict oversight by governmental and/or institutional authorities when trialed on human subjects. Shockingly, the introduction of any new surgical technique often encounters no such oversight. Even more disturbingly, once the technique has been described in the literature (or even social media)—regardless of the volume or quality of the reported experience—it can then be copied and practiced by another surgeon. This again can be done often with little or no oversight. This glitch in modern surgical practice has the potential to harm patients if inadequately proven surgery is unleashed. Perhaps future surgical innovations should be regarded in the same way as a new pharmaceutical drug, and receive the same degree of scrutiny to ensure high standards of safety and ethics.