ABSTRACT: The evolution of surgical oncologic technology has moved toward reducing patient morbidity without compromising oncologic resection. In head and neck surgery, organ-preserving techniques have paved the way for the development of transoral techniques that remove tumors of the upper aerodigestive tract without external incisions and potentially spare the patient adjuvant treatment. The introduction of transoral robotic surgery (TORS) improves upon current transoral techniques to the oropharynx and supraglottis. This review will report on the evolution of robotic-assisted surgery: We will cover its applications in head and neck surgery by examining early oncologic and functional outcomes, training of surgeons, costs, and future directions.
Over the last two decades, the introduction of robotic-assisted surgery has revolutionized minimally invasive surgery in multiple surgical specialties; the successful use of robotics in these other specialties has led to an examination of the potential application of robotic assistance in head and neck surgery. Robotic surgery offers distinct advantages over traditional open and laparoscopic surgical procedures, including smaller incisions, decreased hospital stays, better optics, and improved range of motion of the surgical arms; thus emerging as a standard operation for many procedures in urology, gynecology, general surgery, and cardiothoracic surgery.[1-5] The advantages that robotic-assisted surgery has shown in these fields are achieved without compromising oncologic outcome.
The concept of robots appears to have originated with Aristotle, who imagined independently functioning tools as a means to achieve equality. In the 1960s, General Motors unveiled the Unimate, the first fully functional industrial robotic system. However, it would be another two decades before robots made the transition between the world of manufacturing and that of medicine; when, in the 80’s, robots were introduced in rehabilitative medicine, where they were used to assist patients with day-to-day tasks.
The first robotic surgery system, the PUMA 560, was developed in 1985 to provide greater precision in performing image-guided intracranial biopsies. The PUMA 560 was also used to perform a transurethral resection of the prostate. Further refinement in the early 1990s led to ROBODOC, which improved hardware manipulation in hip replacement surgery. ROBODOC was the first system to receive FDA approval for arthroscopic hip surgery in 1994.
Interest in medical robots led to a collaboration between the National Aeronautics and Space Administration (NASA) and Stanford Research Institute (SRI) in the early 1980’s. Virtual reality consoles were employed to develop telepresence surgery, the virtual placement of a remotely located surgeon in the operative field. The United States military took an interest in this work in an effort to develop a remotely operated robotic system with a dexterous telemanipulator that could stabilize injured soldiers in the battlefield.
Experience with minimally invasive laparoscopic procedures helped surgeons understand the limitations of rigid equipment and two-dimensional views, and this resulted in the development of semi-rigid robotic equipment with three-dimensional views for the operative setting. Combining these tools with telepresence surgery led to the development of the Automated Endoscopic System for Optimal Positioning (AESOP), a robotic arm (controlled by a surgeon’s voice commands) that manipulated an endoscopic camera.[4,9] Shortly thereafter, Intuitive Systems (Sunnyvale, CA) released the SRI Telepresence Surgery System that was recently updated to the current daVinci Surgical System, the most common robotic system in use today.
The daVinci system is a comprehensive master-slave robot with multiple arms operated from a remote console with three-dimensional endoscopic views. To operate this system, the surgeon sits at the console and manipulates the instruments on a patient-side robotic cart, which is cable-driven and provides six degrees of freedom. In the daVinci system, robotic arms are capable of docking 8-mm and 5-mm instruments. The system displays its three-dimensional image above the hands of the surgeon, giving the illusion that the tips of the instruments are extensions of the control grips and creating the impression of being at the surgical site. (Figure 1)
Applications in Other Specialties
Currently, the most common uses of robotic surgery are in general surgery, urology, cardiothoracic surgery, and gynecology. In general surgery, multiple case reports have been published on cholecystectomy, Heller myotomy, Nissen fundoplication, bowel resection with re-anastomosis, splenectomy, and distal pancreatic surgery.[4,5] These reports endorse the benefits of stable visualization and improved dexterity of the robotic arms with suturing and dissection. Gynecologists utilize robotic surgery in hysterectomies, myomectomies, and tubal reanastomoses, and show similarly positive results. Oncologic outcomes were similar to laparoscopic and open methods. However, both specialties noted a disadvantage — the length of setup time both for exposure and for the docking of the robotic arms. Surgeons also observed another major disadvantage; the lack of haptic feedback, which is a virtual tactile feedback technology that provides mechanical feedback to the surgeon.[2,4.5]
Cardiothoracic surgeons have used robotic surgery since 1998, when a German group first performed a series of coronary revascularization procedures and mitral valve replacements. Since that time, multiple other case series have been published describing valve replacements, revascularizations, atrial fibrillation ablations, and congenital cardiac anomalies. Results were encouraging, with evidence demonstrating fewer blood transfusions, shorter hospital stays, faster returns to preoperative function levels, and improved qualities of life compared to data in patient series in which patients underwent a sternotomy.
The field of urologic surgery has perhaps seen the greatest incorporation of robotic surgery: In 2008, nearly two-thirds of prostatectomies were performed with robotic assistance. High-volume centers have shown equivalent positive margin status and reduced PSA levels. Surgeons noted significantly lower blood loss, lower blood transfusion rates and, in some series, less pain and shorter hospital stays than in open prostatectomies. Erectile and urinary functional outcomes were found to be equivalent among open, laparoscopic, and robotic prostatectomies.[1,11-13]
Evolution of Robotic Applications in Otolaryngology
Traditional surgery of tumors of the upper aerodigestive tract has required external approaches that bring the oral and pharyngeal contents into the closed neck space, requiring either local or free flap reconstruction. The addition of a mandibulotomy, which increases visualization and access unfortunately contributes to greater morbidity and poor aesthetic outcomes. These approaches have left patients with varying levels of speech and swallowing dysfunction as well as cosmetic deformity depending on the size and location of the tumor and the extent of resection. Often patients required tracheotomies and feeding tubes, and postoperative recovery included intensive functional rehabilitation that was further slowed by adjuvant chemotherapy and/or radiation.[9,14,15]
In the late 1980s and early 1990s, multiple institutions investigated alternative treatment protocols based on organ preservation without compromising survival. The VA larynx trial and RTOG 91-11 showed that survival rates after following chemotherapy and radiation protocols while preserving the larynx were equivalent to those seen when patients underwent surgery followed by radiation. By preserving the functional laryngopharyngeal complex, these protocols became the standard of care in the treatment of squamous cell carcinoma of the larynx.[16,17] Organ preservation protocols were also applied to other primary sites of the upper aerodigestive tract, with similar survival outcomes. Mendenhall et al reviewed over 6,000 patients treated for oropharynx squamous cell carcinoma (OPSCC) at multiple institutions and found that patients treated with surgery had similar survival rates to those who received radiation as the primary modality. More importantly, he found that patients undergoing surgery first were ten times more likely to have a severe complication or fatality compared to those who had radiation first as part of their treatment. Although the review compiled data from multiple retrospective reviews, the conclusion of this study was that radiation is superior to surgery in OPSCC. This data supports the role of radiation therapy as the primary modality for treatment of this patient population.
Over the last decade, there has been an increase in young, otherwise healthy patients with OPSCC caused by the human papilloma virus (HPV); Fortunately, there is data that shows that these tumors are highly responsive to radiotherapy. Patients with HPV-positive tumors must endure intensive radiation treatments, just as those with HPV-negative tumors do, and since the HPV-positive patients are younger, there is a greater potential for long-term sequelae from radiation, such as osteonecrosis or radiation-induced malignancy.[20,21] Head and neck surgeons are then faced with a dilemma of providing oncologic cure without affecting functional performance in this era of organ preservation. While it is unclear whether these HPV-positive tumors are more susceptible to all types of treatments or whether we are simply identifying patients at an earlier stage, the development of successful minimally invasive surgical techniques may serve to control the tumor locally and spare patients from undergoing radiotherapy, which can be used later if the patient develops either a local recurrence or a second primary.
Transoral laser microsurgery (TLM) was introduced in the 1970s for ablation of laryngeal papillomas. It has since evolved to encompass treatment of early laryngeal cancers, showing excellent local control rates without compromising vocal function. TLM has only recently been evaluated for its clinical efficacy in OPSCC. While there have been no randomized trials comparing surgery versus radiation, small series from various institutions have shown success at achieving local control in using TLM as the primary modality for OPSCC. At the Mayo Clinic, 69 patients with OPSCC
(T-stage 1-3) were treated with TLM without adjuvant therapy and after a 44-month follow-up period, local control was achieved in 66 patients. In Germany, a team led by Wolfgang Steiner showed an 85% local control rate at five years when using TLM for OPSCC, with 52% of the patients not requiring adjuvant radiotherapy. However, the rigid equipment and the narrow-field view through the laryngoscopes used in TLM make it a challenge to maneuver within the complex anatomy of the oropharynx.
Robotic surgery provides a unique advantage by introducing optics and instrumentation with multiple degrees of rotation that allows for access to the entire pharyngeal surface. In addition to this, the three-dimensional camera can be positioned close to the tumor, which provides an excellent view of the surgical bed. In the following sections, we will discuss the development of TORS and review the early data on oncologic and functional outcomes.