Transoral robotic surgery using CO₂ laser in oropharyngeal squamous cell carcinoma: a clinical case series

Abstract

Purpose

Transoral robotic surgery (TORS) is an established surgical approach for oropharyngeal squamous cell carcinoma (OPSCC). Carbon dioxide (CO₂) laser offers high cutting precision and minimal collateral thermal injury, yet its use in TORS remains underreported. The purpose of this study is therefore to describe the first UK case series detailing the use of CO₂ laser via hollow waveguide in TORS.

Methods

Eight patients (six male, two female; mean age 60 years) presenting with either left tonsillar (seven cases) or right tongue base (one case) OPSCC underwent primary TORS resection with CO₂ laser at a tertiary UK head and neck centre between October 2020 and May 2024. Cases were selected based on tumour stage, anatomical suitability and patient preference. The CO₂ laser (SmartXide Trio, 3–10 W, ultra-pulse mode) was delivered via hollow waveguide mounted on one of the arms of the Da Vinci robotic system. Outcome measures included histological margin status, peri- and postoperative complications, swallowing function, and hospital length of stay.

Results

All tumours were completely excised; two of the eight had close margins on the primary specimen but were clear on additional sampling. No intraoperative complications occurred, and all procedures were completed without conversion. All patients resumed oral intake without nasogastric feeding. Mean hospital stay was 2.75 days, with no airway compromise, catastrophic bleeding, or significant swallowing dysfunction.

Conclusion

CO₂ laser dissection in TORS for OPSCC represents a viable surgical approach with acceptable postoperative functional outcomes and may possibly demonstrate reduced thermal injury compared with monopolar electrocautery.

Introduction

Transoral robotic-assisted surgery (TORS) has become popularised in the UK for head and neck oncological procedures such as tongue-base mucosectomy for investigating cancer of unknown primary and for the treatment of early-stage oropharyngeal squamous cell carcinoma (OPSCC). TORS obviates the need for open surgery by providing a 3-dimensional view of a relatively small surgical field as well as enhanced surgical dexterity facilitated by endo-wristed instruments for precision tissue handling and dissection.

The incidence of oropharyngeal squamous cell carcinoma (OPSCC) has been rising in the UK and other developed nations, primarily attributable to human papillomavirus (HPV), which is now responsible for over 70% of cases in Europe and the USA [1]. According to the latest UK guidelines for OPSCC management, published in 2016, early-stage disease should be treated with a single modality - either primary surgery or radiotherapy (RT) [2, 3]. The principal treatment objective is to achieve effective regional disease control whilst maintaining function, such as safe swallowing. Evidence indicates that both surgical and non-surgical approaches yield comparable long-term survival outcomes [4]. Consequently, the decision between surgery and RT should be based on patient preference, individual suitability, and likelihood of preserving normal function.

Carbon dioxide (CO₂) lasers are a well-established surgical instrument in head and neck surgery due to several favourable characteristics such as high cutting precision, effective haemostasis and limited collateral thermal injury, having demonstrated clear benefits in relation to excellent oncological results and functional outcomes in selected cases [5]. CO₂ laser wavelength (10.6 μm) is absorbed by water and causes vaporisation of tissue with minimal carbonisation resulting in a clear operative field [6]. Transoral laser surgery as a primary treatment for OPSCC pre-dates TORS by almost a decade [6, 7]. The introduction of hollow waveguides, which safely transmit CO₂ laser energy through flexible fibres, has expanded its use in head and neck surgery. This technology has also enabled the use of CO₂ lasers for TORS procedures as an alternative to conventional monopolar electrocautery [8, 9]. However, there remains a paucity of literature describing the use of CO₂ laser in TORS procedures.

Therefore, the objective of this case series is to share our team’s experience with using the CO₂ laser via hollow waveguide for TORS resection of OPSCC, demonstrating its feasibility.

Materials and methods

At our tertiary head and neck centre in the UK, between October 2020 and May 2024, eight TORS procedures were performed using CO₂ laser for primary surgical resection of OPSCC (one case was performed in October 2020 as a pilot case, and the subsequent cases were performed from June 2023 onwards). Following discussion at the head and neck multi-disciplinary team meeting, each case was selected for TORS resection based on the clinical and radiological staging of the primary tumour, patient suitability for TORS (e.g. adequate mouth opening, neck flexion, dentition) and patient choice. The use of the CO₂ laser as the resection modality was dependent upon training demands, since the high level of skill required to operate the laser precluded its use by new trainees. Therefore, the laser only tended to be used when the operating surgeon was not engaged in training. All procedures were performed by the same operating surgeon. All patients received the local standard postoperative TORS analgesia protocol. Informed, written consent was obtained from all patients that were included in this case series and the reporting guideline used was SCARE - consensus-based surgical case reports guideline [10]. The main outcome measures of this case series include safety and efficacy of the CO₂ laser for TORS resection of OPSCC, and assessment of peri- and postoperative complications. Data was also collected on the size of the primary tumour, histological margins and hospital length of stay.

The procedures were all performed using the Da Vinci robotic surgical system (Intuitive Surgical, Sunnyvale, CA, USA; initially an SLE model, then later an X model) according to the manufacturer’s specifications. Three operating arms of the robot were utilised: a camera port, 8 mm Maryland bipolar forceps and a needle driver to hold and manoeuvre the armoured cable housing the hollow waveguide (Fig. 1). The CO₂ laser equipment used for all cases was SmartXide Trio (DEKA, Italy) in ultra-pulse mode with power settings between 3 and 10 watts. The laser energy was delivered using a hollow waveguide inside an armoured introducer (Fig. 2) held by the Da Vinci needle driver. The introducer tip had a spatula design allowing for blunt tissue dissection whilst protecting the exposed end of the hollow waveguide from tissue coagulation or damage. The laser pedal is placed in the footwell of the Da Vinci console (Fig. 3). Laser safety checks were performed as per hospital policy and a reinforced laser endotracheal tube was used in all cases.

Fig. 1.

Image of the Da Vinci robotic system during a TORS case. All three robotic arms are shown working in the space of the patient’s oral cavity, to include (from left to right) a needle driver to hold and manoeuvre the armoured introducer containing the hollow waveguide, a camera port and an 8 mm Maryland bipolar forceps

Fig. 2.

Image of the armoured introducer showing the aperture from which the red laser fibre protrudes 2–3 mm, note the laser fibre does not protrude beyond the tip of the triangular spatula plate immediately below it

Fig. 3.

Image showing the footwell of the Da Vinci console with the laser pedal visible second from left with a black cable attached, this can be placed adjacent to the electrocautery foot controls which are located on the right-hand side of the footwell

Results

In this case series, six patients were male and two were female with an average age of 60 years (range 49–79 years). Of the eight cases, seven had a primary tumour of the left tonsil and one had a primary tumour of the right tongue base. seven of the eight cases were clinically and pathologically staged as T2 tumours with one T3 (left tonsil) as per international staging standards (AJCC 8th Edition) (Table 1). The average maximum dimension of the primary tumours was 32.38 mm (range 21–46 mm). On histological examination, two of the eight cases demonstrated close margins (defined as < 1 mm) on the main specimen but on examination of further specimens taken from adjacent tissue, there was no tumour present. All primary tumours were therefore considered completely excised. Seven of the eight cases had an ipsilateral selective neck dissection (level 2–4) as part of their oncological treatment. The patient with the tongue base tumour also had a staged contralateral neck dissection. All cases were completed successfully using the CO₂ laser without the need to convert to an alternative dissection instrument. There were no intraoperative complications such as catastrophic bleed, airway fire, or inadvertent injury to the teeth or jaw. All patients returned to the general ENT ward postoperatively, with no requirement for higher-level care. No patients required a nasogastric (NG) tube for nutrition postoperatively and almost all patients were established on a satisfactory oral diet before discharge (see Table 2). The average length of stay was 2.75 days (range 1–6 days). One patient had an in-patient length of stay of 6 days due to postoperative pain, which was never adequately explained. No other post operative complications were recorded.

Table 1.

Summary data for all included cases where TORS was combined with CO₂ laser as a dissection tool

Case	Age (years) /Sex	Clinical staging	Pathological Staging	Max Length (mm)	Length of Stay (days)	Complications
1	61/M	T2 N1	pT2 pN2	32 mm	2 days	None
2	59/M	T3 N0	pT3 N0	46 mm	4 days	None
3	67/M	T1 N1	pT2 pN2	30 mm	2 days	None
4	65/M	T2 N1	pT2 pN1	36 mm	3 days	None
5	52/M	T2 N1	pT2 pN1	34 mm	2 days	None
6	49/F	T1 N1	pT2 pN1	21 mm	6 days	Pain
7	50/M	T2 N1	pT2 pN1	37 mm	2 days	None
8	79/F	T2 N0	pT2 Nx	23 mm	1 days	None

Table 2.

Summary of post-TORS swallow function and dietary modifications. Modified oral intake refers to whether patients required modifications to their usual diet postoperatively. 

Case	Modified oral intake after surgery (Yes (Y)/No (N))	Observed Aspiration (Yes (Y)/No (N))	Day 5 Liquid/ Solid	Day 14 Liquid/ Solid	Post-Op NG feeding (Yes (Y)/No (N))	Length of time to return to baseline diet level (days)
1	Y	N	No data	L0, L7	N	14 days
2	Y	Y	L0, L5	L0, L6	N	25 days
3	Y	N	L0, L7EC	L0, L7EC	N	Not achieved
4	Y	Y	L0, L4	L0, L6	N	4 weeks
5	Y	Y	L0, L7EC	L0, L7	N	13 days
6	N	N	L0, L7	L0, L6	N	0 days
7	N	N	L0, L7	L0, L7	N	0 days
8	N	N	L0, L7	L0, L7	N	0 days

These were classified into levels according to the International dysphagia diet standardisation initiative (IDDSI) Framework. Levels of diet: L0 (thin fluids), L1 (slightly thickened fluids), L2 (mildly thickened fluids), L3 (moderately thickened fluids or liquid foods), L4 (extremely thickened fluids or pureed foods), L5 (minced and moist foods), L6 (soft foods), L7EC (regular easy to chew), L7 (regular diet). Observed aspiration refers to aspiration during bedside swallowing assessment. This consisted of observation of swallow, palpation of hyo-laryngeal movement and noting of any overt signs of aspiration such as coughing. Please note that no data was recorded in the medical notes for case 1 on day 5 and that for case 3 return to baseline diet was not achieved before the commencement of adjuvant treatment (though did return to baseline after the conclusion of all treatment)

Discussion

In this case series our team found the CO₂ laser, delivered through the hollow waveguide, to be a safe and effective dissection tool for oropharyngeal TORS procedures. Firstly, the CO₂ laser provided precise, well-defined tissue dissection. As there is no physical contact between the fibre and the tissue, the dissection field is not obscured (Fig. 4). Additionally, we noted that CO₂ laser results in minimal tissue charring, thereby preserving clear dissection margins which is consistent with observations reported in previous studies [9, 11]. A notable distinction between laser and monopolar electrocautery dissection in TORS patients is the amount of energy delivered to the pharyngeal tissues during dissection. Laser devices generally operate at 5–10 W of power, and technologies such as Super-Pulse and Ultra-Pulse enable the laser to alternate on and off at microsecond intervals, which can reduce collateral thermal spread compared to continuous laser settings. In contrast, monopolar electrocautery is typically used at 30 W with an effect size of 2 or 3, aiming to limit energy delivery while still ensuring effective cutting and coagulation [12]. Some TORS surgeons employ higher power settings; for example, the Intuitive system defaults to 150 W for coagulation and 180 W for cutting unless customised. The higher power delivered by monopolar electrocautery may be a factor contributing to increased postoperative pain and prolonged hospital admissions reported in the literature [13]. The CO₂ laser with lower power, together with the TORS system, therefore has the potential to mitigate some of the functional impacts of OPSCC resection.

Fig. 4.

Intraoperative photograph demonstrating bipolar Maryland forceps (right hand instrument) medialising tissue for left lateral oropharyngectomy with mucosal incision being made using CO₂ laser delivered via the hollow waveguide fibre (left hand instrument), the reinforced laser endotracheal tube is also visible on the far right of the image

We observed that the minimal thermal injury to surrounding tissue led to limited post-operative pain (apart from case 6) and generally rapid recovery of swallow function. The average length of stay in hospital for our patient cohort was 2.75 days with no patients requiring nasogastric tube feeding at any stage following surgery. Similar findings were reported by Benazzo et al. who found that there was a significant improvement in postoperative recovery and overall function with patients who had laser resections with TORS compared with electrocautery [9]. Furthermore Karaman et al. reported reduced bleeding, pain and swallow dysfunction using laser compared with electrocautery for tongue base resection to treat obstructive sleep apnoea [13].

Although detailed analysis was outside the scope of this report, it is reasonable to suggest that the precise dissection and minimal tissue charring associated with CO₂ laser assisted histopathologists in accurately evaluating tissue margins. Hoffman and colleagues conducted a histological comparative analysis of various resection tools used in TORS and found that on microscopic evaluation the CO₂ laser resulted in a narrower incision width and a reduced coagulation zone compared to monopolar electrocautery [8]. Furthermore, Benazzo et al. reported that electrocautery was associated with significantly higher rates of close or positive margins on resected specimens when compared to CO₂ laser [9].

The major limitation of this study is that it is an uncontrolled case series with a relatively small study population. Therefore any observed benefits of using the laser could also relate to other factors such as surgical technique or institutional protocols relating to postoperative care. We hope however that by demonstrating the viability of coupling CO₂ laser and TORS, that this opens the door toward larger scale, controlled studies. Technical limitations when using the hollow waveguide then include the need for the operator to be conscious of the working distance of the laser to the tissue, in order to maintain optimal energy delivery and prevent excessive beam divergence. On occasion, tissue coagulation also soiled the laser fibre and the cable had to be removed in order to cleave and revive the laser fibre tip, adding time to the procedure. We anticipate with further experience this can be mitigated. For TORS resection of larger tumours, CO₂ laser would also be ideal for adopting the Steiner approach, described for laryngeal tumours, to preserve pharyngeal musculature [14]. Although we have not conducted a cost analysis as part of this case series, it stands to reason that the consumables as well as the initial cost for the CO₂ laser generator is considerably more than for a monopolar device.

The increasing use of TORS in the UK has resulted in transoral laser microsurgery (TLM) becoming less common, as surgeons are now required to acquire new skills and perform approximately 15–20 cases annually to maintain proficiency. The adoption of TORS introduces new procedures for theatre staff, anaesthetists, ward staff, speech therapists, specialist nurses, and patients. All members involved in the patient pathway for TORS are expected to gain relevant experience and knowledge pertaining to these procedures. As a result, the practices developed from TLM have become less prominent. CO₂ lasers are widely utilised in many head and neck units for transoral microscopic laryngeal resections, suggesting that integration of this technology with TORS procedures would be practical for most departments where TORS is routinely performed. Accordingly, we consider our findings to be both relevant and generalisable to other UK centres conducting TORS procedures. Notably, this case series is the first to report the use of the CO₂ laser as a resection instrument in TORS within a UK centre.

Conclusion

The application of CO₂ lasers in TORS is a viable hybrid approach in head and neck surgery. Although the body of evidence is currently limited, available studies indicate that utilising CO₂ lasers as a dissection tool could potentially provide significant benefits over monopolar electrocautery such as enhanced tissue margin preservation and decreased collateral thermal injury [8]. These factors may then contribute to advantages such as improved functional outcomes and lower postoperative pain which have been observed in the literature [9, 13]. Our case series demonstrates the feasibility of incorporating the CO₂ laser in TORS, and we recommend that head and neck units with access to this technology strongly consider its implementation.

Author contributions

T.K undertook preliminary literature review and then both T.K and D.C wrote the main manuscript text and prepared relevant figures. A.C was instrumental in gathering data from electronic medical notes. J.M was the primary operating surgeon on the included cases. All authors reviewed the manuscript. As corresponding author T.K then formatted the paper and ensured it met all relevant pre-submission guidelines. During the process of responding to reviewer comments, A.C also helped to further elucidate the data. The revised manuscript and the response to reviewer comments were written and re-written by both T.K and J.M.

Funding

Financial support was received from Lynton Lasers to cover publishing expenses. None of the named authors have any financial ties to Lynton Lasers or any other companies producing CO₂ lasers or robotic systems. The funder (Lynton Lasers) had no role in the method design, data collection, analysis nor writing of the final manuscript.

Data availability

All relevant data is included in Tables 1 and 2 as part of the submitted manuscript.

Declarations

Competing interests

Financial support was received from Lynton Lasers to cover publishing expenses. None of the named authors have any financial ties to Lynton Lasers or any other companies producing CO2 lasers or robotic systems. The funder (Lynton Lasers) had no role in the method design, data collection, analysis nor writing of the final manuscript.