Nd-YAG laser–assisted pulmonary metastasectomy: initial experience from a tertiary care cancer center in India

Abstract

Introduction

Pulmonary metastasectomy is recommended for metastatic lung lesions when R0 resection is possible, the primary site is in controlled status, surgery is of low risk, and extrathoracic metastases are absent. We present the initial experiences of laser-assisted surgery (LAS) for pulmonary metastatic lesions from a tertiary care cancer center in India.

Materials

All patients undergoing non-anatomical pulmonary metastasectomy between September 2022 and January 2023 for synchronous and metachronous lesions, operated on by a single consultant thoracic oncosurgeon in a tertiary care center of India, were identified from a prospective database. Ten patients with 124 metastatic lesions were included in the study. A hybrid approach (video-assisted thoracoscopic surgery (VATS) with mini-thoracotomy) was performed. Measurements of total lesion volume and lung parenchyma resected were taken from the final histopathological analysis of the intraoperative sample.

Results

LAS was performed for 102 lesions and stapled wedge resection for 22 lesions. Evidence of malignancy was noted in 88/102 (86.3%) of the lesions excised. Patients with LAS had advantages of parenchyma preservation, less postoperative morbidities, and shorter hospital stays.

Conclusion

LAS of pulmonary metastatic lesions addresses more lesions in a single sitting; the bilateral lung lesions can be operated and has parenchyma preserving and good sealant properties.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12055-024-01723-8.

Introduction

The lung is the second most common site of metastases from malignancies occurring in other parts of the body following the liver [1].

The benefits of metastasectomy of the lung have always been in doubt with no substantial evidence in randomized controlled trials (RCTs). There was a scarcity of data on pulmonary metastasectomy (PM) in the early days until 1997 when the first report from the International Registry of Lung Metastasectomy was published [2].

Since then, a number of studies have been published that showed the survival benefit of PM in various cancers. The recent Pulmonary Metastasectomy versus Continued Active Monitoring in Colorectal Cancer (PulMiCC): a multicentre randomized clinical trial (PulMiCC trial) was conducted to see the efficacy of PM in comparison to active monitoring. Although it stopped recruitment in 2019, the limited dataset showed that the 5-year absolute survival benefit with metastasectomy is about 35%: 40% after metastasectomy compared to < 5% in controls. The estimated survival in this study was 38% (23–62%) for metastasectomy patients and 29% (16–52%) in the well-matched controls [3].

In current practice, it is broadly accepted that the objective of the metastasectomy is to achieve complete resection of all pulmonary metastatic tumors and to preserve as much functioning lung parenchyma as possible all the more so as redo-PM may be required. To this end, non-anatomical lung wedge resection, widely performed by staplers, is often the preferred surgical procedure for limited and peripherally seated lung nodules [4, 5].

However, for central lesions (any lesion in the vicinity of either of the two main bronchus with diameter > 3 cm is considered ‘central large lesion’ in the study), pulmonary segmentectomy, lobectomy, and eventually pneumonectomy may be required. In cases of centrally located metastases and low functional reserve in which wedge resection is not possible, or in the presence of multiple metastases, the utility of laser-assisted pulmonary resection and electrocautery has become increasingly popular [6, 7].

Cautery resection was described by Perelman in 1983 [8]. This method consists of coring out the metastasis by means of coagulating the surrounding lung tissue and ligating small vessels and bronchi within the resultant cavity. Electrocautery when used in high-power settings not only generates smoke but also the carbonized tissue sticks to the tip of the cautery, which hinders its handling. Additionally, middle-size vessels bleed if not properly coagulated and also air leakage and fistula are a matter of concern because the resection surface is cauterized in an irregular manner [9]. Because of the above-mentioned reasons, this technique has seldom been applied solely by a thoracoscopic approach.

In this study, we used a hybrid approach with video-assisted thoracoscopic surgery (VATS) and mini-thoracotomy. Laser-assisted surgery (LAS) was performed using a neodymium-doped yttrium aluminum garnet (Nd:YAG, Nd: Y3Al5O12) laser (1320 nm; Limax, KLS Martin GmbH & Co. KG, Tuttlingen, Germany) (shown in Fig. 1). Very few centers in India are currently using it. To the authors’ knowledge, this is the first report on PM using Nd-YAG laser from the Indian subcontinent. It presents our initial experiences with laser-assisted PM and aims to look for the efficacy of Nd-YAG laser in performing more PM, which preserves more parenchyma than the traditional approach, and has fewer complications and brisk recovery.

Fig. 1.

The Limax® 120 Nd:YAG laser (Gebrüder Martin GmbH & Co. KG, Tuttlingen, Germany) monitor along with a glimpse of the main unit with a corrugated smoke evacuator attached (inset)

Materials

All patients undergoing non-anatomical sub-lobar PM between September 2022 and January 2023 for synchronous and metachronous lesions, operated on by a single consultant thoracic oncosurgeon at a thoracic surgical oncology unit in a tertiary care center in India, were identified from a prospective database. Additional data was collected retrospectively from patient records from PARAS software, operative recordings, and clinical imaging systems.

Measurements of total lesion volume and lung parenchyma resected were taken from the final histopathological analysis of the intraoperative sample. However, these data do not represent the exact volume as lung volumetry was not done. Only the nodule/resected parenchyma ratio was used in this study.

Follow-up data for radiological and clinical outcomes was recorded from a prospectively maintained database.

Clinical course

Patients were referred to the thoracic oncology (surgical) unit through respective specialist multidisciplinary team/tumor board discussion.

In those patients with an indication for PM, the decision for LAS or traditional stapled wedge metastasectomy (SWM) was taken by the consultant surgeon. LAS was preferred in patients who had more lesions, even in central large lesions, and in those who had undergone previous lung metastasectomy.

Bilateral metastases were tackled both as a single procedure or as staged procedures, with an interval of 4–6 weeks, depending on postoperative recovery.

All procedures were performed under general anesthesia, with single-lung ventilation using a double-lumen endotracheal tube. A 10-mm port incision for diagnostic thoracoscopy with 10-mm 30 scope along the posterior axillary line (PAL) 7th intercostal (IC) space was performed first. This was followed by a posterolateral serratus-sparing mini-thoracotomy (7 cm) along the 5th IC space (Fig. 2).

Fig. 2.

Intraoperative image showing mini-thoracotomy wound with an Alexis retractor. Neodymium-doped yttrium aluminum garnet (Nd-YAG) laser probe is being used for excision of a peripheral nodule with assistance of a wide bore high-performance suction system

LAS was performed using the Limax® 120 Nd:YAG laser (Gebrüder Martin GmbH & Co. KG, Tuttlingen, Germany) along with a high-performance smoke evacuator (Fig. 3 and supplementary video file containing details of the procedure). Post excision, lung parenchyma was repaired with 3–0 non-absorbable continuous suturing. The intraoperative air leak was then checked at a ventilation pressure of 30 mmHg.

Fig. 3.

LAS being performed using the Nd:YAG laser for a deeper placed parenchymal nodule. LAS, laser-assisted surgery; Nd-YAG, neodymium-doped yttrium aluminum garnet

At the end of the operation, a single large-bore pleural drain (usually a 28-Fr intercostal drainage (ICD) tube) was placed in the pleural cavity and set to low-pressure suction.

All patients were managed in surgical intensive care unit (ICU) on post operative day (POD) 0. They were stepped down to the general ward on POD 1 morning and nursed there until discharge. IC drain was removed once the chest X-ray showed an expanded lung and no air leak was evident on clinical examination.

Results

A total of 10 patients underwent Nd-YAG laser–assisted procedures during the given time period. The dataset for primary disease and disease-free interval in the case of metachronous pulmonary metastases is depicted in Tables 1 and 2.

Table 1.

Distribution of study population according to primary, treatment received, and types of metastases

Primary	Site	Treatment	Metastases
Malignant phyllodes	Breast	MRM > adj RT	Metachronous
Embryonal rhabdomyosarcoma	Gluteus	NACT	Synchronous
Osteosarcoma	Femur	NACT > LSS**** >  Adjuvant CT	Metachronous
Adeno ca rectum	Rectum	NACTRT > APR > Adjuvant CT	Metachronous
MPNST	Groin	NACT	Synchronous
NSGCT (2 cases)	Testis	CT > RA-RPLND	Synchronous
Ewing sarcoma	Iliac bone	NACT	Synchronous
Synovial sarcoma	Elbow joint	NACT > WLE > Adjuvant RT	Metachronous
ccRCC	Kidney	Right CN > Bilateral VATS metastatectomy	Metachronous

MPNST malignant peripheral nerve sheath tumor, NSGCT non-seminomatous germ cell tumor, MRM modified radical mastectomy, NACT neoadjuvant chemotherapy, LSS limb salvage surgery, APR abdominoperineal resection, RA-RPLND robot-assisted retroperitoneal lymph node dissection, WLE wide local excision, ccRCC clear cell renal cell carcinoma, CN cytoreductive nephrectomy, RT radiation therapy

****LSS limb salvage surgery

Table 2.

DFI measured in case of metachronous tumors

Primary	DFI in months
Malignant phyllodes	41
Osteosarcoma	34*
Adeno ca rectum	27
Synovial sarcoma	22
ccRCC	85*

DFI was measured from the date of completion of last tumor-directed therapy until the date of diagnosis of lung metastases

*DFI disease-free interval was measured from the date of primary VATS metastatectomy. In these two cases, laser-assisted surgery was taken up as re-do metastatectomy

Bilateral lung metastases were found in 5 patients. Four among them (80%) underwent single-staged laser-assisted metastatectomy. The average number of lesions encountered in these 4 patients was 5 (range 3–19). One patient (non-seminomatous germ cell primary) underwent a two-stage metastasectomy as the number of lesions was high (total 19 in both lungs) and in view of the requirement for excision of para-aortic mass (teratoma). While a staged procedure is conventionally described for bilateral lesions, we were able to do a single stage procedure in 80% of the cases. When stage procedure is planned, an interval of 4 to 6 weeks is recommended.

The total number of metastatic lesions encountered was 124 in 10 patients. Metastatectomy with Nd-YAG laser was performed for 102 lesions (82.25%) and stapled wedge resection for 22 lesions, 17.75% (Fig. 4). Among the 102 nodules treated with laser excision, 88 nodules showed evidence of malignancy (88/102; 86.3%).

Fig. 4.

Total number of lesion and procedure done

In all the patients, a hybrid approach consisting of VATS with a mini-thoracotomy was performed.

Among the lesions excised by laser, the mean size of the nodule was 1.675 cm × 1.3 cm × 0.7 cm and the mean size of the specimen excised was 2.18 cm × 1.44 cm × 0.95 cm with a mean documented clear margin of 2.6 mm (range 1–6 mm).

Nodule/specimen ratio using the laser method was calculated as 0.52.

The median lymph node sample was 5 (range 3–12). This was done in 7 cases where either there was preop evidence of an enlarged lymph node or intraoperative detection of an enlarged suspicious node. Whole-body positron emission tomography (PET) scan showed mild activity (standardized uptake value (SUV max) < 2) in all 7 cases. A total of 37 nodes were harvested. None of them had any evidence of malignant involvement in final histopathology.

The most common complications in the early postoperative period encountered were air leaks and basal pneumonitic changes. Two patients showed signs of air leaks in the early postoperative period until day 2. Each one had previously undergone stapled wedge resection. They resolved spontaneously with conservative management and were discharged on day 6. The mean duration of hospital stay was 4.8 days with 4.1 days (range 3–7 days) in laser-assisted cases and 5.5 days (range 4–8) in patients where stapled wedge resection has been done along with laser-assisted excision.

Chest drains were removed once there was no evidence of air leaks and chest X-ray showed an expanded lung. Following the removal of the ICD, the patients were observed for 1 day and were discharged. The mean time of ICD removal in laser-assisted cases was 3.1 days and 4.5 days in cases/sites where wedge resection was also done (intra- and postoperative details in Table 3).

Table 3.

Overview of treatment details

Type	Number of lesions	Mean nodule size in cm	Mean excised specimen in cm	Nodule/specimen ratio	Margin in mm	Air leak	Basal pneumonia	ICD removal in days	Stay in days
LAS	102	1.6 × 1.3 × 0.7	2.2 × 1.4 × 0.9	0.52	2.6	-	-	3.1	4.1
SWM	22	1.8 × 1.7 × 1.6	7.2 × 3.6 × 1.7	0.11	7.3	2	2	4.5	5.5

LAS laser-assisted surgery, SWM stapled wedge metastatectomy

Discussion

Approximately 30% of patients with malignant tumors will develop pulmonary metastases. PM is an established treatment with low morbidity and mortality rates in selected patients with lung metastases [5, 10, 11].

These patients may benefit from a lung resection with curative intent as part of an oligometastatic concept. A PM is generally indicated if the primary tumor is controlled with no effective systemic agents and significant disease-free interval in cases with adequate cardiopulmonary reserves [12–14].

In 1997, the results of the International Registry of Lung Metastases from 5206 patients from Canada, the USA, and Europe showed evidence of survival prolongation after PM in select groups [15].

However, no prospective randomized trials have compared PM with other therapeutic options. Nevertheless, surgical resection of pulmonary metastases is widely performed as part of the treatment for various primary tumors. The 5-year survival rate after PM ranges from 20 to 80% [16].

Currently, PM is recommended in two situations:

• A.
  The first one when done with curative intent requires fulfillment of predetermined criterions:

  1. Controlled primary
  2. No evidence of extrapulmonary metastatic site
  3. Low risk for surgery
  4. R0 resection possible for lung metastases
• B.The second one is to sample the suspicious pulmonary nodule when the primary is in controlled status and there is suspicion of a second primary other than the pre-existing malignancy.

Now, there are various methods for PM. It all started with lobectomy, followed by sub-lobar resections and the use of staplers, electrocautery, ultrasonic scalpels, and more recently laser-assisted excisions. Laser-assisted excision was first done by Minton in 1967 [17]. In 1985, LoCicero used a CO₂ laser that was considered inadequate for PM [18]. However, after the development of multiple laser devices, centers in Europe, Japan, and the USA began performing laser-assisted PM with 1064 Nd:YAG. Finally, in 2007, the development of the 1318 Nd:YAG, which could deliver 100 W, allowed resections of many lung metastases while reducing postoperative thermal tissue edema. Mineo et al. and Rolle et al. in 1994 and 2006 actually raised the issue of the importance of using laser for PM in recent times [19, 20].

They emphasized mainly two points. One, laser can be useful for addressing a larger number of metastatic lesions. Two, reresection is feasible in cases where the previous excision has been done with the assistance of an Nd-YAG laser.

In the current scenario, laser-assisted PM is commonly practiced in a few Western countries. There are very few centers in India where the Nd-YAG laser is being used for PM. This can be done both via VATS and thoracotomies (anterolateral preferably) or with a hybrid approach. The main usefulness is that a larger number of lesions can be excised at one time without adding significant morbidity to the patient. Even bilateral lung metastasectomy can also be performed if the number of lesions is limited. However, we prefer a two-stage operation separated by 4–6 weeks. The side with a higher number of lesions is addressed first.

Evolution and rationale of laser-assisted surgery

Lobar and sub-lobar resection resulted in the sacrifice of a significant amount of parenchyma. The electrocautery had the disadvantage of charring/necrosis of 5–10 mm normal parenchyma beyond the resection line. Kirschbaum et al. reported that monopolar cutters caused more adjacent tissue injuries than lasers [9]. The newly introduced laser has a good sealing property, and tissue necrosis is less, as was evident in our case, and quite handy in addressing densely placed parenchymal vessels in lung tissue, which has got almost 80% water and low tissue density [4]. Lung tissue and exposed bronchioles are sutured with non-absorbable sutures to prevent air leaks.

The purpose of PM is to ensure R0 resection (clear resection margins with no microscopic and macroscopic disease left in the patient), which ensures prolonged survival. In one previous study, it was reported that laser leaves behind a 5-mm margin of carbonated zone. This, in turn, was divided into vaporization zone, coagulation zone, and hyperemia zone [6]. This provides a good adequate margin, as was proposed by Rolle et al. [7] that a 3-mm safety margin and an additional 5-mm coagulation zone are adequate to minimize the local relapse rate.

Hassan et al. showed that resection of two or fewer metastases resulted in recovery of lung function (diffusing capacity of the lungs for carbon monoxide (DLCO)) after 3 months. Also, a decline of DLCO in the whole cohort correlated with the number of resected metastases at 3 months and at 6 months, as well as the parenchymal depth. These results are comparable with resection techniques [21].

The main advantages of laser-assisted metastasectomy in the lung appear to be:

1. more number of nodules can be dealt with;

2. bilateral lung field metastasectomy can be addressed in a single surgery with less morbidity; and

3. previously centrally located moderate to large size metastases warranted surgery like lobectomy. The use of laser may avoid this and preserve a significant amount of lung parenchyma.

Limitations

1. Education about laser in operation room (OR) staff including safety guidelines is of utmost importance.

2. Efficacy in deeper lesions not yet proved.

3. Paucity of RCT comparing laser technique with the conventional techniques.

Recently, local ablative therapies like radiofrequency ablation/stereotactic body radiation therapy (RFA/SBRT) are also being used in some centers. The ablation efficacy of these modalities is very good. The disadvantage is that tissue confirmation may not be possible after RFA/SBRT. Nd-YAG laser, on the other hand, has good ablative properties and the excised tissue is available for final histopathology.

Conclusion

The current era of oncology practice emphasizes on ‘less is more’ wherein the focus remains on maximal organ preservation without compromising oncological safety. Laser-assisted metastasectomy definitely improves the pulmonary parenchyma preservation without compromising the margins of resection. Overall morbidity is less with lesser days of hospital stay.

Supplementary Information

Below is the link to the electronic supplementary material.

Author contribution

Conceptualization: LD, AC.

Methodology: LD, AC.

Software: AC.

Validation: LD, PS.

Formal analysis: AC, PS.

Investigation LD, AC.

Resources: LD, PS.

Data curation: PS.

Writing—original draft: AC.

Writing—review and editing: AC, LD.

Visualization: LD.

Supervision: LD.

Funding

None.

Declarations

Ethical considerations

This study was discussed in the Institutional Review Board at our institution and was approved (RGCIRC/IRB-BHR/96/2022).

Informed consent

A proper informed consent was obtained from the patients before writing this report quoting the details.

Statement of human and animal rights

The study includes human patients. Before proceeding with the study, proper consent was taken, Institutional Review Board clearance was taken, and identities of individuals were not revealed.

Conflict of interest

The authors declare that they don’t have any conflict of interest.