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24 Advancements in Transoral Robotic Surgery and the Treatment of Oropharyngeal…
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Retractor Systems
While robotic technology addresses limitations of minimally invasive non-robotic
surgery, such as eld of view and optimizing the use of limited surgical space, the
feasibility of transoral robotic surgery is often restricted by impediments to surgical
site exposure. TORS technology requires the development of innovative retractor
systems to improve the interface between the robot and the surgical site.
Tonsillectomy is the most common ablative oropharyngeal surgery performed.
Mouth gags commonly used in oropharyngeal surgery—the McIvor, Crowe-Davis,
and Dingman retractors—have been adapted for use in robotic surgery. Most widely
used retractor systems resemble the Dingman retractor, which was developed at the
University of Michigan in the 1960s. Like the McIvor and Crowe-Davis retractors,
it has a tongue blade to displace the oral tongue inferiorly. Its extended closed frame
includes buccal retractors that improve the eld of view and allow more light into
the operative eld (Fig.24.2).
Fig. 24.2 Retractor systems commonly used in oropharyngeal robotic surgery. (Top left) Dingman
retractor. (Top right) Laryngeal Advanced Retractor System (LARS). (Bottom left) FK-WO retractor system. (Bottom right) Flex retractor system (gure adapted from catalog photos from vendors
of each retractor)
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The rst retractor system adapted for use in TORS is the Feyh-Kastenbauer (FK)
(Gyrus Medical Inc., Tuttlingen, Germany). It is a closed-frame, rectangular-shaped
retractor with a wide variety of tongue blades. Its unique tongue-retracting blades
are designed to improve distal access to the tongue base and beyond. It also offers
optional use of articulating cheek retractors that can be xed to the frame. The original FK retractor was further modied by Weinstein and O’Malley. It may also be
referred to as the FK-WO retractor system. The modications of the FK-WO system
optimize the interface with the da Vinci robot, and the system also includes a variety
of tongue blades to extend use to the larynx and hypopharynx.
The Laryngeal Advanced Retractor System (LARS) (Fentex, Tuttlingen,
Germany) was introduced by Remacle et al. in 2011 [8]. This closed-frame,
rectangular- shaped retractor has a wider horizontal dimension than the FK-WO system, which is more vertically oriented. The LARS framework also has bended
curves that can aid in preventing contact with the robotic arms. It also comes with a
variety of blades which make this retractor system amenable to surgery in the oral
cavity, oropharynx, larynx, hypopharynx, and cervical esophagus.
Medrobotics Corporation (Raynham, MA, USA) designed the Flex Retractor,
which was originally designed to be used in conjunction with their Flex Robotic
System [9]. Like the LARS and FK-WO, the Flex Retractor is a closed frame with
interchangeable tongue-retracting blades and articulating clamps for cheek retractors. The frame is almost square shaped with a slightly longer vertical dimension.
Like the LARS, it has a rounded frame to adapt to the curvature of the face. Like the
FK-WO, it has a feature to adjust the blade angle. Unique to the Flex Retractor is
the ability to adjust the axial rotation of the tongue blade. The tongue blades also
have suction integrated into their design.
Success in TORS is incumbent upon gaining favorable exposure of the primary
tumor. As applications of robotic surgery grow, so will the need for innovative solutions to the limitations of access in minimally invasive surgery.
G. M. I. Low and J. M. Bigcas
Augmented Reality inTransoral Robotic Surgery
Augmented reality (AR) is an interactive experience where the real-world environment is enhanced by computer-generated objects to create a mixed perceptual reality for the user. The AR market has tremendous potential for application in surgical
technologies and education. The following are a few examples of AR technology:
• Superimposed rst-down markers in televised football games.
• Simultaneous localization and mapping in map/navigation software.
• Filters and superimposition enhancements in social media photo-taking.
• Online furniture stores using cell phone cameras to show potential customers
how a particular piece would t and look in their home or ofce before purchasing.
• Online clothing stores using camera technology to show how their product would
look on potential customers.
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419
There are different types of augmented reality. The types of AR that have applications in robotic surgery include location-based AR, projection-based AR, and
superimposition/overlay AR.Location-based AR interweaves virtual 3D objects
in physical space. In this type of augmented reality, virtual objects are tied to realworld physical locations. When the camera points at that location, the virtual
object is projected on the camera. This is different from projection-based augmented reality. Projection-based AR uses machine vision technology, which may
combine visible light cameras with 3D-sensing systems to project images onto
actual physical objects. The projections are visible to all the people in that physical space. In overlay AR, the physical object is seen by the user as replaced by a
virtual object.
With the surgical robotic system as the interface between the surgeon and the
surgical site, augmented reality (AR) technologies can provide additional information, cues, and alarms to improve surgeon performance. Forte and Kuckenbecker
classied ve tool categories for AR in robotic surgery [10].
• Virtual markers.
• Computational tools.
• Rehearsal of procedure.
• Visual alarms.
• Viewing patient data.
Within otolaryngology, augmented reality technologies seem to be gaining popularity as power users nd more applications. Wong et al. found that publications
outlining AR technologies in otolaryngology have increased between 1997 and
2018 [11]. In their study, they found 23 articles representing 18 AR platforms. Most
were in the rhinology subspecialty (52%), followed by head and neck (30%) and
otology (26%). The most common use was intraoperative guidance (55%), followed
by surgical planning (24%) and procedural simulation (9%). Visual input was
mostly from endoscopes (50%), eyewear (22%), and microscopes (4%). Endoscopic
sinus surgery lends itself well to augmented reality use cases because of its foundation in endoscopes and the prolic use of intraoperative navigation. Robotic head
and neck surgery has similar application potential, yet research and applications are
still nascent.
In traditional open head and neck surgery, surgeons rely on experience,
vision, and tactility. The robot, however, creates an altered depth of eld, and
the visual input interfaces with the surgeon’s eyes through the endoscope. The
robot also does not provide the surgeon with tactile information or haptic feedback. Robotic surgeons learn to overcome the sensory decits inherent to robotic
surgery and rely more heavily on high-denition 3D vision. These are opportunities to implement AR tools that can augment robotic surgery, which in turn
create a safer operating environment for the surgeon and the patient. One such
example is intraoperative navigation. In sinus surgery, intraoperative navigation
is a widely used technology. It not only facilitates the procedure but also helps
identify structures to avoid, such as the skull base and the orbit. It also is a powerful intraoperative educational tool for trainees and educators. Integration of
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G. M. I. Low and J. M. Bigcas
image overlay to augment robotic surgery has been described. Tsang etal. performed a cadaveric study to demonstrate the potential for intraoperative navigation during robotic nasopharyngectomy [12]. The technology is still in its
infancy and application, and use cases are likely to expand.
For trainees, surgical simulation can provide additional repetitions of transoral robotic surgery. Preoperatively, there are opportunities for rehearsing procedures and using imaging that can be integrated for intraoperative navigation
to avoid structures like the carotid arteries. Intraoperative information about the
patient, such as their imaging, can be available on-screen and integrated into the
visual experience of the surgeon. Tools to measure depth or distance can have
potential application in AR-assisted robotic surgery. Catastrophic bleeding is
the most feared complication in transoral robotic surgery. It is a common practice to ligate branches of the external carotid artery and/or the external carotid
artery itself to avoid such a bleed [13]. Visual markers, alarms, and superimposition AR can potentially herald avoidable structures relative to your specimen
and current location in the operative eld. Liu etal. described various applications of augmented reality for invivo tumor resection [14]. Chan etal. described
a cadaver experiment where they were able to perform image-guided robotic
surgery in soft tissue [15]. A major issue in intraoperative navigation for neck
surgery is the lack of constant landmarks and deformable nature of soft tissue.
They were able to register a 3D virtual model of the cadaver to maxillary dentition, which allowed them to overlay the course of the internal carotid artery
(Fig.24.3).
Augmented reality is an early technology with numerous applications. With the
robotic technology at the interface between the surgeon and the surgical site, surgeons can continue to develop tools to augment the surgical experience.
Fig. 24.3 Figure adapted
from Chan etal.
demonstrating
superimposition
augmented reality of the
location of the internal
carotid artery (white
arrow) within soft
tissue [15]
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421
Extended Applications ofRobotic-Assisted Surgery
intheHead andNeck
Hypophyarynx
Cancer of the hypopharynx has a particularly poor prognosis within head and neck
cancer, and surgery in this area has largely been the realm of open surgery due to
the difculty of access through the natural orice pathway. A recent systematic
review looked at TORS approaches to the hypopharynx and found that robotic surgery was used successfully for tumor extirpation in this site; however, the robot was
utilized primarily for lower T-stage disease. Cumulative survival was found to be
85.5% (95% CI 55.8%–96.5%). The single-port robot has been utilized more extensively for hypopharynx tumors due to greater mobility of the wristed instruments [16].
Larynx
From the beginnings of robotic-assisted surgery, head and neck surgeons have used
the robot to access tumors of the larynx, utilizing the superior optics to help visualize tumors both supraglottic and endolaryngeal. TORS approaches have been used
in endoscopic partial laryngectomy with good results. However, even with the
smaller instruments of the single-port model, the robot has increased bulk compared
to transoral laser microsurgery (TLM) approaches, and proponents of TLM will be
quick to point out the technique’s greater versatility and long track record of use in
the supraglottis and glottis. Despite this, the utility of the robot for this area continues to grow as techniques improve and adapt to use in the larynx. For example, the
use of a wide, at tongue retractor in the FK-WO retractor system can be used to
move a signicant amount of tongue out of the way and improves access of the
instruments to the larynx [17] (Fig.24.4).
Fig. 24.4 Larynx
specimen being removed
from oral cavity during
robot-assisted transoral
total laryngectomy (gure
reproduced from Smith
etal. [18])
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Robotic total laryngectomy has been performed and published in several small
case series. The surgery adds signicant operative time and still requires a small
external incision for formation of the tracheostoma. The surgery itself builds
from the techniques of endoscopic partial laryngectomy and is an interesting
technical application of the da Vinci robot. Patient selection, as is the case for all
TORS patients, is key, and at this time, only salvage laryngectomy patients not
requiring neck dissection have undergone robotic total laryngectomy in the literature [18].
G. M. I. Low and J. M. Bigcas
Thyroid
Remote access thyroidectomies have been performed as early as the late 1990s.
However, the use of the robot to assist in visualization was rst adopted in 2005. At
that time, access was through the axilla, using the Si iteration of the da Vinci robot.
Other techniques described include a retro-auricular approach and, most recently, a
transoral approach. Intraoperative nerve monitoring is recommended for each of
these approaches.
The American Thyroid Association notes that remote access thyroid surgery
should only be performed in extremely high-volume remote access thyroidectomy centers, and they have published very strict guidelines for patient selection.
Importantly, surgery should only be performed on the least complicated subjects,
avoiding large nodules, abnormal anatomy, prior thyroiditis, or prior surgery.
Even in optimal cases, each approach carries additional risks that are not present
with traditional open thyroidectomy. Transaxillary approaches have resulted in
brachial plexus injuries. Temporary injury to the greater auricular and marginal
mandibular nerves has been reported with the retroauricular approach. Injuries to
the mental nerves have been reported in the transoral approach. Routine postoperative antibiotics are recommended after the transoral approach, as compared to
no antibiotics being recommended with open thyroidectomy. All remote access
thyroidectomy techniques have an increased operative time and increased cost.
However, for the patient who is interested in scarless or remote scarring after
thyroidectomy, these costs may be worth it as assessed on a case-by-case
basis [19].
Parotid
The use of the robot has also been explored for a reduction in postoperative skin scar
appearance after parotidectomy. A series of 40 supercial parotidectomies were
performed by a group from Seoul. Thirty-two of these tumors were benign, and 8
were malignant. Some of these procedures were accompanied by robotic neck
24 Advancements in Transoral Robotic Surgery and the Treatment of Oropharyngeal…
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dissection. Mean operative time for these surgeries was 226min for parotidectomy
and 375min for parotidectomy with neck dissection. There were three patients with
a transient (<1month) facial weakness in their series but no cosmetic decits at
6 months. As with other robotic-assisted surgeries utilized for cosmesis, robotic
parotidectomy with or without neck dissection provides a smaller skin incision in
exchange for a signicantly longer operative time. Like robotic thyroidectomy
approaches, concerns remain regarding learning curve and iatrogenic morbidity
during the learning period [20].
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Nasopharynx
Just as the robot allows for surgery “around the corner” into the hypopharynx, studies have shown proof of concept for use in the nasopharynx. Using a transoral
approach, preclinical studies have shown the ability for the robot to be used in extirpation of nasopharynx tumors with or without division of the soft palate. Tumors of
the nasopharynx traditionally respond well to radiotherapy, and thus surgery is usually utilized in the setting of recurrent or persistent disease. The limitations previously discussed (cost, operative time, size mismatch of instruments to operating
space) all also apply to robotic surgery of the nasopharynx [21].
Robotic-Assisted Reconstructive Surgery
One of the downsides of robotic oropharyngectomy over a large open procedure is
the increased difculty in reconstructing a large defect. Smaller defects can be left
to heal by secondary intention, and patients tolerate this moderately with minimal
scar formation albeit with signicant postoperative pain. Traditionally, a large open
ablation of the oropharynx would be closed with a free ap reconstruction. Inset
into this area has been performed with the assistance of the robot with good success.
This does increase surgical time signicantly, but with good patient selection, there
is a signicant reduction in morbidity [22]. A group in Taiwan has also successfully
performed robotic-assisted microvascular anastomoses for their free ap reconstructions with good success [23].
Robotic Surgery inDe-escalation Therapy
forOropharyngeal Cancer
Traditional open approaches to the oropharynx are complicated and carry major
comorbid risk. These approaches include lip-split mandibulotomy and pharyngotomy. A study by Parsons et al. [24] compiled data from 51 studies from 1970 to
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G. M. I. Low and J. M. Bigcas
2000, looking at outcomes of over 6400 oropharyngeal cancer cases, comparing
surgery +/− adjuvant radiotherapy to denitive radiotherapy +/− posttreatment
neck dissection and found that the overall survival between the two groups was the
same, but severe and fatal complications were signicantly higher in the surgery
group. Naturally, practitioners during that period shifted to paradigms favoring radiation over surgery. From 1985 to 2000, primary chemoradiation doubled in the
United States, while surgery and primary radiation declined. Primary chemoradiation became the gold standard for treating oropharyngeal cancer.
Advancements in the understanding of human papillomavirus (HPV)-driven oropharyngeal cancer led to further considerations for de-escalation therapies.
Compared to HPV-negative disease, HPV-positive squamous cell carcinoma was
found to have a much better prognosis. In a multi-institutional study by Ang etal.,
they examined the outcomes of radiotherapy on a 323-patient cohort of advanced
oropharyngeal squamous cell carcinoma—206 with HPV-positive disease [25].
Three-year survival was 82% in the HPV-positive group versus 57% for the HPVnegative group. There was a 58% reduction in risk of death for HPV-positive disease. As more patients survive the epidemic of p16+ oropharyngeal cancer, they
also must live with the complications of radiation therapy, including lymphedema,
radiation scarring, trismus, xerostomia, and dysphagia. As our understanding of
oropharyngeal cancer and its treatment continues to evolve, what is the appropriate
amount of treatment? Can we optimize survival and decrease morbidity?
Robotic surgery has become a centerpiece in the era of new de-escalation paradigms for oropharyngeal cancer. There are four basic categories of treatment
de-escalation:
• Reduction in radiation doses and volume.
• Alterations in chemotherapy dose and frequency.
• Chemoradiation-combined de-escalation.
• Upfront surgery +/− adjuvant radiation.
Particularly for early stage (low T, low N) oropharyngeal cancers, TORS has
become a widely accepted alternative to radiation. Studies have shown similar survival outcomes comparing radiation to TORS for HPV-positive disease. Not surprisingly, there is evidence to suggest that TORS for HPV-negative disease has superior
outcomes [26] to radiation. In the appropriately selected patient, TORS is a minimally invasive technology that can achieve similar results to open approaches to the
oropharynx with less morbidity and operating room time. Avoiding a mandibulotomy or pharyngotomy—procedures rife with potential for immediate and long-term
complications—is, in some ways, a form of surgical de-escalation. Since the rst
descriptions of TORS by O’Malley and Weinstein in 2005, its adoption has
increased, while a concomitant decrease in primary radiation therapy has been
observed in early stage T1/T2 oropharyngeal cancers [27] (Fig.24.5).
In the ideal TORS patient, a cure is possible with surgery alone and no need for
adjuvant radiation or chemotherapy. Surgery consists of resection of the primary
tumor with the indicated neck dissection. Histopathologic analysis of the tumor and
neck dissection specimens identies adverse features where adjuvant therapy may
U.S Adoption of TORS and the Decline of Primary
1
l
carcinoma and rates of adverse pathologic features: features: National Cancer Data Base, 122(10): 1523-1532
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Radiation for T1/T2 Oropharyngeal Cancer
2011
50%
45%
40%
35%
30%
2005
25%
U Penn TORS
Human Trial
20%
% Patients, Primary Radiation Only
15%
2004 2006 2008
Note: TORS procedure frends come from Infuitive Surgical internalsales data
Primary radiation data is limited to the timeframe between 2004 and 2013.
Cracchiolo, J., Baxi, S., Morris, L., Ganly, I., Patel, S., Cohen, Roman, B. (2016). Increase in primary surgical freatment of T1 and T2 oropharyngeal squamous cel
Fig. 24.5 This gure from Cracchiolo etal. demonstrates the shift paradigm of TORS adoption
for early-stage oropharyngeal cancer [27]
provide some survival advantage. These features include close or positive margins,
perineural invasion, lymphovascular invasion, extranodal extension, large positive
lymph node(s), multiple positive nodes, and atypical metastatic pattern. The indications for adjuvant chemotherapy or radiotherapy may vary among practitioners.
Though the intent may be to achieve single modality surgical cure, there is always
the possibility for strongly recommended adjuvant therapy in the form of radiation
or chemoradiation. There is a growing body of literature demonstrating that upfront
surgery can achieve comparable results with lower-dose, de-escalated adjuvant radiation compared to full-dose adjuvant radiation.
Randomized trials comparing TORS to radiation and their respective functional
outcomes and survivals are sparse. The ORATOR study, published in 2019, is one
such study [28]. Sixty-eight patients with T1–T2N0–2 were randomized to either
TORS with neck dissection (with or without adjuvant chemoradiation based on histopathologic features) or radiation therapy (70Gy, with chemotherapy if N1–2).
While there were expected higher rates of neutropenia, hearing loss, and tinnitus in
the radiation group, the surgical group had higher rates of trismus. Interestingly,
MD Anderson Dysphagia Index (MDADI) scores were higher in the radiation group
(86.9 with SD 11.4) than the surgery group (80.1 with SD 13.0). Clinically meaningful change in MDADI score is detected when a 10-point difference occurs
between groups. Thus, the difference between groups does not qualify as meaningful clinical change in quality of life 1-year posttreatment. The study’s 3-year follow up update again demonstrates improved dysphagia in the RT arm over surgery.
However, the differences in MDADI scores between groups are of a smaller
NCCN guidelines
remove primary radiation
as preferred treatment for
early oropharyngeal
cancer
2009
FDA clearance
for TORS
removal T1/T2
fumors
2010
2012
2014
FDA clearance
for TORS benign
base-of-tongue
resection
2014
425
Primary Radiation%
TORS Procedures
2016
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G. M. I. Low and J. M. Bigcas
magnitude than at the 1-year posttreatment time point. The researchers also strongly
recommended tracheostomy to every TORS patient following a postoperative death
due to oropharyngeal bleeding. The presumed high prevalence of tracheostomies in
the TORS group is an additional confounder for mild dysphagia in the immediate
postoperative period.
National Comprehensive Cancer Network guidelines outline paradigms for radiation dosing; however, local radiation and medical oncology paradigms vary from
practice to practice. Pertinent to TORS, postoperative radiation therapy or concurrent chemoradiation is recommended within 6weeks of surgery, and the indications
are based on histopathology. For high-risk cancers with adverse features, the recommended dose of adjuvant radiation is 60–66Gy (2.0Gy per fraction for 6–6.5weeks).
For low or intermediate risk, the dosing recommendation can vary from 44 to 50Gy
in 3D-CRT to 54–63Gy for IMRT.While the ideal TORS patient is still a clinical
T1 or small-T2 primary tumor with single nodal disease with no radiologic or clinical evidence of extracapsular spread, it seems that there has been a shift away from
primary radiation and toward more surgery. Surgery provides invaluable staging and
histopathologic information that can spare or decrease the need for high-dose radiation or chemoradiation. In an early study of TORS-inspired de-escalation, Weinstein,
Quon etal. applied postoperative radiation at 54Gy in 24 patients (12 with radiation
alone and 12 indicated for chemoradiation) [29]. They had one recurrence in an
unoperated contralateral neck. As we learn more about behaviors of oropharyngeal
cancers, we can investigate to pursue lower doses of adjuvant radiation. Three large,
randomized trials are currently deployed looking at postoperative de-escalation
paradigms—ECOG 3311, ADEPT, and PATHOS.
ECOG 3311 is a study currently in follow-up that examines de-escalated adjuvant treatment in patients receiving TORS.The study design includes 511 patients
with AJCC seventh edition stage III-IV HPV-positive oropharyngeal cancer who
underwent TORS and stratied them based on risk. There is a low-risk arm, which
included pT1–T2N0–1 with >3mm margins, and they receive no adjuvant therapy.
Intermediate risk patients (close margin, < 1mm ENE, 2–4 metastatic nodes, perineural or lymphovascular invasion) were randomized into two groups—one receiving 50Gy and the other receiving 60Gy. The high-risk group (positive margins, >
1mm ENE, > 4 positive nodes) underwent chemoradiation with radiation dosed to
66Gy. Three-year survival update was given at ASCO in 2021 [30]. All four arms
of the study had greater than 90% progression-free survival (PFS). The low-risk
group had similar survivals to both randomized intermediate-risk groups. Within the
randomized intermediate-risk groups, functional outcomes were better in the lower
dose treatment arm. Patients who received radiation alone had better swallowing
outcomes compared to the triple-modality treatment received by the high-risk
group. Though the data of this phase 2 study should be interpreted with caution, it
heralds a victory for de-escalation.
The ADEPT trial (NCT01687413) is a phase III trial out of Washington University
School of Medicine. This study examines adjuvant therapy in p16-positive oropharyngeal cancer (n=496) where TORS achieved negative margins and the neck dissection demonstrates extracapsular extension. The adjuvant arms include
chemoradiation (60Gy+weekly cisplatin 40mg/m2) versus radiation alone (60Gy),
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