The oropharynx is the part of the throat directly behind the mouth(Fig.1). It includes the tonsils, base of tongue, soft palate and posterior pharyngeal wall.
Squamous cell carcinoma is the commonest malignant tumour that occurs in oropharynx. It is often seen in older men who have a history of smoking and drinking. However, over the last 10 to 20 years, oropharynx cancers are increasing in incidence and seen in patients who are younger, healthier and non-smokers. This is attributed to human papillomavirus (HPV) and is associated with oral sex.
HPV-associated oropharynx cancers have a better prognosis than patients with non-HPV associated oropharynx cancer with current treatment.
Because the oropharynx helps in breathing, eating, and talking, patients may need special help adjusting to the side effects of the cancer and its treatment. Depending upon the tumour size, location and stage, your doctor may recommend treatment.
The three main types of treatment for these cancers are surgery, radiation and chemotherapy. Most of these tumours get cured with a combination of chemotherapy and radiotherapy. Traditional open surgery is reserved for residual or recurrent (tumours that have not disappeared or reappeared after chemoradiation) tumours. To avoid the side effects (dryness of throat causing difficulty in swallowing and talking) of radiation, surgeons use minimally invasive procedures through the mouth using Laser, endoscope and robot for small tumours.
Fig.4. In open surgery, the lip is split in midline and the lower jaw (mandible) is divided to expose the tumour
The surgeon gains access to the tumour by splitting the lip and mandible (lower jaw) (Fig.4) which will be plated together at the end of the procedure without causing any deformity. After removal of the tumour, the defect is reconstructed. Surgery may affect how the patient eats, breathes or talks. Open surgery was reserved for residual or recurrent tumours.
There is a minimally invasive option for patients diagnosed with early throat cancer. Using the da Vinci robot or endoscopic ultrasonic instrunents the surgeon removes the tumour through the mouth. For early tumours of tonsil, base of tongue, posterior pharyngeal wall and supraglottis, Transoral Robotic Surgery (TORS) or Transoral Ultrasonic Surgery (TOUSS) should be the treatment of choice. It avoids the morbidity of chemoradiation as well as open surgery. For advanced tumours, chemoradiation should be the treatment of choice and open surgery should be reserved as a salvage procedure.
In select patients, robot-assisted minimally invasive surgery is performed. Transoral robotic surgery (TORS) gives the surgeon an enhanced view of the tumour and the surrounding tissue. Using a da Vinci robotic surgical system, the surgeon guides surgical tools through the mouth to access the tumour and remove/ resect it. This technique provides the surgeon with increased precision and stability. TORS reduces morbidities associated with traditional open surgery, thereby reducing hospital stay and aiding in faster recovery.
During transoral robotic surgery, surgeon sits at a remote control console (Fig.5) a short distance from the operating table.
The mouth is kept open with special retractor. Three arms of the robot go through the open mouth armed with camera and two instruments(Fig.6).
Using two special joystick-like instruments known as endowrist instruments, the surgeon guides very small tools at the ends of the robot arms to remove the cancer(Fig.7). Robot allows more-precise tremor-free movements in tiny spaces. The surgeon’s console displays a magnified, 3-D view of the surgical area that enables the surgeon to visualize the procedure in much greater detail.Tumours can be dissected free from surrounding tissue safely.The machine is not a true robot (it does not operate or move by itself), but is a “master slave” unit. This means the surgeon is in complete control throughout the procedure, and controls the instruments at all times.
This technique is a surgical alternative to the Transoral Robotic Surgery. During a TOUSS (Fig.8) the surgeon uses endoscopic ultrasonic tools through the mouth to access the oropharyngeal tumour. TOUSS reduces morbidities associated with traditional open surgery, thereby reducing hospital stay and aiding in faster recovery.
Patients with early stage tumours (T1 or T2) with limited lymph node involvement in the neck are suitable candidates for TORS and TOUSS. Approximately 20 to 30 percent of patients with oropharyngeal (tonsils and tongue base) tumours may be considered ideal candidates for the procedure. Patients with certain tumours of the larynx and throat may also be candidates. Patients who smoke tobacco or have Human Papilloma virus (HPV) negative tumours are especially encouraged to receive surgical treatment for their cancer, as these cancers often do not respond as well to radiation and chemotherapy.
The doctor may recommend rehabilitation to improve speech and swallowing function post-surgery.
