Robotic-assisted lobectomy for malignant lung tumors.

Objectives: For patients with lung cancer, surgical resection remains the best curative option and is associated with the longest disease-free survival. We present our institutional outcomes treating pulmonary malignancy with robotic lobectomy over the course of 1 year.
Methods: A retrospective review was conducted on patients who underwent robotic pulmonary lobectomy for malignancy at a single institution in 2018.
Results: Over the course of 1 year, 166 patients underwent robotic lobectomy for pulmonary neoplasm. The mean age of the patients was 75 years; 73% were current or prior smokers and 52% of the patients were male. The mean body mass index was 28 kg/m2. Conversion to open thoracotomy occurred in 7% of patients. The mean total hospital length of stay (LOS) was 3 days. Histopathological examination revealed a mean tumour size of 2.7 cm with 11 lymph nodes harvested. Left-sided tumours had a significantly higher number of lymph nodes harvested when compared to right-sided tumours (11.6 vs. 9.8, P = 0.01), despite sampling the recommended minimum of three N2 stations. The most common pathology was adenocarcinoma (65%), followed by squamous cell carcinoma (17%) The 30-day operative mortality was 0.6%. Conclusions: Robotic video-assisted thoracoscopic surgery is a safe, feasible and oncologically adequate procedure for lung malignancies. Comparison of our outcomes to previously reported national averages suggests a similar hospital LOS, lymph node harvest, conversion rate to open thoracotomy and 30-day mortality rate. We acknowledge the limitations of this non-randomised, retrospective study. Future research on robotic lobectomies is encouraged.

INTRODUCTION

Lung cancer continues to be the leading cause of cancer-related mortality in the United States and worldwide. For operable patients with clinical stage I and II non-small cell lung carcinoma, surgical resection remains the best curative option and is associated with the longest disease-free survival.[1] Pulmonary resections by video-assisted thoracoscopic surgery (VATS) have firmly been established as a safe and favourable approach for resection of pulmonary neoplasm when compared to the traditional open thoracotomy. Several studies have shown improved post-operative outcomes with comparable long-term efficacy and survival of VATS when compared to thoracotomy.[2345]

Nevertheless, the two-dimensional visualisation and the limited range of motion of thoracoscopic instruments make VATS lobectomy technically challenging. Robotic surgery with the da Vinci robot (Intuitive Surgical, Sunnyvale, CA, USA) offers several technical advantages including a high definition, three-dimensional field of view, improved dexterity and tremor filtration. Given these advantages, the implementation of robotic technology in thoracic surgery continues to increase with recent studies, suggesting equivalence to VATS as a minimally invasive approach.[678910]

Our objective in this study was to review the outcomes of our single-centre, high-volume tertiary community healthcare institution and identify the benefits of using the robotic-assisted technology in highly complex thoracic procedures such as pulmonary anatomic resections.

METHODS

Data source

After approval from the institutional review board, a retrospective departmental database was established for patients who underwent robotic lobectomy for pulmonary malignancy in 2018. All patients selected for pulmonary lobectomy underwent pre-operative workup with computed tomography (CT) scan of the chest and/or positive emission tomography (PET) scan. Pulmonary function tests were routinely utilised to predict the post-operative pulmonary function. Cases were performed by one of two surgeons. Robotic lobectomy was performed using the da Vinci surgical robot Xi platform. Carbon dioxide insufflation was universally used and a four-port system was utilised in most operations. A complete mediastinal lymph node dissection was routinely performed followed by separate ligation and division of the lobar vessels and bronchi.

Statistical analysis

Data are organised by the anatomic lobe resected – right upper lobe, right middle lobe (RML), right lower lobe, left upper lobe and left lower lobe. The data are expressed as n, percentage or as the mean ± standard deviations. Continuous data were compared using either Student's t-test or analysis of variance. A P < 0.05 was considered statistically significant. Data were analysed using Microsoft Office Excel (Microsoft, Redmond, WA, USA).

RESULTS

Over the course of 1 year, a total of 166 patients underwent robotic lobectomy for malignant pulmonary disease. There was a fairly even distribution of gender, with 52% of patients being male. A majority 73% of the patents were current or former smokers. The mean age of the patients was 75 years (74.6 ± 9.6) and the average body mass index (BMI) was 28 kg/m2(27.5 ± 6.2). Pre-operative patient characteristics are delineated in Table 1. For patients, the mean length of stay (LOS) in the intensive care unit was 1 day (1.1 ± 0.3). The mean hospital LOS was 4 days (3.6 ± 2.3), with a median LOS of 3 days. Thirty-six per cent of patients were discharged home within the first 48 h. Typically, one chest tube was placed at the time of surgery and the mean duration of time that this remained in place was 3 days (3.0 ± 2.1) with a median duration of 2 days.

Table 1

Pre-operative characteristics of patients organised by anatomic lobe compared to all patients overall

	Average age (years)	Males (%)	Smokers (%)	BMI
Overall	74.6	48	73	27.5
RUL	76.2	50	70	27.8
RML	76.8	53	60	29.1
RLL	73.7	55	80	27.7
LUL	74.4	65	70	27.5
LLL	71.2	34	80	27.3

BMI: Body mass index, RUL: Right upper lobe, RML: Right middle lobe, RLL: Right lower lobe, LUL: Left upper lobe, LLL: Left lower lobe

The average tumour size was 2.7 cm [2.7 ± 2.8, Figure 1]. All procedures included a mediastinal lymph node dissection with enlarged or suspicious lymph nodes resected. The mean number of complete lymph nodes harvested without nodal subdivision was 11 [10.6 ± 3.5, Figure 2]. No single anatomic lobe had a significant difference in the number of lymph nodes harvested when compared to the overall mean. However, left-sided tumours had a significantly higher number of lymph nodes harvested when compared to right-sided tumours (11.6 vs. 9.8, P = 0.01).

Figure 1

Mean tumour size organised by anatomic lobe with a cumulative mean size of 2.7 cm (2.7 ± 2.8)

Figure 2

Mean number of lymph nodes harvested from each operation, organised by anatomic lobe. On average, each operation yielded a total of 11 lymph nodes (10.6 ± 3.5)

The conversion rate to open thoracotomy was 7% of all procedures (12, 7.2%). Emergent conversion for bleeding was encountered in only one patient with the remaining semi-elective conversions driven by poor lung isolation or significant air trapping in patients with severe emphysema or anatomic vascular abnormalities. The RML was the only anatomic lobe that was able to be resected robotically with no procedures converted to open. The most common pathology encountered was adenocarcinoma (108, 65%), followed by squamous cell carcinoma (28, 17%) and then carcinoid (12, 7%). Nine patients (5%) had metastatic disease from distant primary sites. The remaining 5% of patients had large cell (4, 2%), adenosquamous (4, 2%) or small cell lung carcinoma (1, 1%). These data are organised as shown in Figure 3. There was only one death within 30 days of operative date, making the 30-day mortality rate 0.6%. This particular patient developed an acute stroke post-operatively requiring an additional intervention, which was complicated by respiratory failure at which point the family decided to pursue withdrawal of care.

Figure 3

Pathology encountered in tumours resected from each anatomic lobe

CONCLUSIONS

After its initial description in the 1990s, the adoption of VATS has played a key role in the advancements in thoracic surgery. Several studies have supported the use of VATS when compared to open thoracotomy for pulmonary resection.[2345] VATS is associated with a decreased hospital LOS, improved post-operative pulmonary function, decreased pain and lower morbidity.[3] Given these advantages, the utilisation of minimally invasive techniques in thoracic surgery continues to increase. Data from the Society of Thoracic Surgeons General Thoracic Surgery Database reveal an increase in VATS for anatomic lung resection from 8% in 2003 to 43% in 2009.[11] More recent data show that 62% of anatomic lung resections were completed either via VATS or RVATS in 2012–2014.[12]

The use of robotic systems has further enhanced the development of minimally invasive thoracic surgery. The wristed robotic instruments allow for an increased ranged of motion when compared to the straight thoracoscopic instruments, which is especially advantageous during dissection within the confines of the bony thoracic cavity. In addition, the superior high definition visualisation, increased tremor filtration and improved ergonomics make robotic surgery a favourable alternative to VATS.

There is a growing body of literature that recognises both the safety and feasibility of RVATS for pulmonary lobectomy. Several large nationwide series suggest similar morbidity and mortality rates of RVATS when compared to VATS.[1314151617] Rajaram et al. analysed outcomes of robotic lobectomies between 2010 and 2012 from the National Cancer Data Base.[18] Examination of this nationwide series reveals comparable results to data from our cohort. The mean hospital LOS in our cohort is 4 days compared to the previously recorded national mean of 6.1 days.[18] Further analysis revealed a median LOS of 3 days; the increased mean LOS likely represents those patients who remained hospitalised with a chest tube due to a prolonged air leak. In our cohort, 36% of patients were discharged home within the first 48 h. The mean number of lymph nodes examined in our robotic lobectomies was 10.6 compared to the national mean of 9.9. The conversion rate to open thoracotomy was seen in 7% of procedures in our experience, which appears comparable to historical reports documenting a conversion rate between 2% and 13%.[192021]

When compared to VATS, RVATS has been largely shown to have similar oncologic outcomes including nodal harvest, surgical resection margins and long-term survival.[13141822] However, a few select studies have suggested that RVATS is associated with improved nodal harvest when compared to VATS.[23242526] In our cohort, the left-sided tumours had a higher number of lymph nodes harvested when compared to the right-sided tumours. Data from the American College of Surgeons Oncology Group Z0030 trial that analysed differences between patients who underwent VATS lobectomy to those who underwent thoracotomy revealed no statistical difference in the overall number of lymph nodes harvested between right- and left-sided tumours.[27] Previous studies have reported a 30-day mortality rate range of 0.2%–2.5%, which places our operative mortality rate of 0.6% on the lower end of this spectrum.[2829]

Scepticism about robotic surgery includes the significant costs associated with the technology such as the upfront capital costs of the machine itself as well as the increased costs associated with the supplies and maintenance. There is an on-going discussion regarding the costs associated with robotic surgery in comparison to the money saved with possibly decreased hospital LOS and complications.[30] A limitation of this study is not reviewing costs. Cost of procedure and overall cost-effectiveness of RVATS were not within the scope of this study.

This study is limited by its non-randomised retrospective analysis of patients undergoing RVATS without a matching cohort as a control group. The study design does not allow for a direct comparison to be done between RVATS, conventional VATS and open thoracotomy. In addition, as different surgical approaches are adopted by different surgeons, it is difficult to delineate which outcomes may be surgeon-specific compared to the surgical approach. Surgical outcomes may be more related to a surgeon rather than the operative approach.

Despite the limitations of this study, we believe that the results from our institution support the notion that RVATS can safely and reliably be used to perform a minimally invasive lung resection with systematic lymphadenectomy. The technique of robotic lobectomy continues to be an evolving technique, and further studies are needed to fully analyse the added value of robotic surgery in the field of thoracic surgery.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.