Nasopharyngectomy with the da Vinci Surgical Robot

Abstract

Nasopharyngeal carcinoma (NPC) is the 7th commonest cancer in Hong Kong. Improvements in radiotherapy had increased the cure. Unfortunately, up to 10% of the patient still suffered from local recurrence. Because of the deep location, nasopharyngectomy was considered a difficult operation. Developments in surgical approaches had now established nasopharyngectomy as a standard salvage for locally recurrent NPC. With improvements of endonasal endoscopic instruments and endoscopic techniques, endoscopic nasopharyngectomy as a minimally invasive surgery for salvaging small locally recurrent NPC have been reported in several cohorts with encouraging results. Robotic nasopharyngectomy remained difficult due to tight operation space and instrument considerations.

The da Vinci surgical robot was marketed in 1999 as a tool to assist surgeons in performing complex surgical manipulations in tight spaces. It was later adapted to be used in the upper aerodigestive tract for endoscopic resection of small cancers transorally. As the da Vinci surgical robot was not designed for head and neck operations, adaptations are required when we tried to apply it to resect tumours in the nasopharynx.

The present study aimed to develop the use of the da Vinci surgical robot to perform minimally invasive operations on the nasopharynx in a cadaveric model. Ten procedures on 3 cadavers were performed with the surgical robot. Due to instrument clutter, a transoral approach was preferred over transnasal approach. In transoral approach, the soft palate obstructs the access to the nasopharynx. We devised three approaches, namely palatal suspension approach, midline palatal split approach and lateral palatal flap approach. We also assess the advantages and limitations of the three approaches.

From 2010-2014, 18 robotic nasopharyngectomies were performed. Median operation time was 232 minutes (range 125-574). Estimated median blood loss was 100ml (range 100-1800). Negative margins were achieved in 14 patients. The two-year actuarial local control was 83% and estimated mean survival was 42.7 months (95% confidence interval 35.0-50.3 months). A positive or close margin was significant associated with poor local control but not overall survival. Results were comparable to open or endoscopic nasopharyngectomy.

There was no 30 days post-operative mortality but one patient suffered from hypoxic brain damage after developing angioedema in the recovery room. Two patients developed permanent palatal fistulas and one patient had severe trismus after operation. Symptomatic osteoradionecrosis occurred in three patients.

When comparing the quality of life assessment with patients after open maxillary swing nasopharyngectomy operation, robotic nasopharyngectomy patients have a higher score in social functioning scale and lower symptoms scores on pain, mouth opening and social eating. The global health score and other functioning scores were statistically not different.

Robotic nasopharyngectomy is a feasible minimally invasive operation for resecting selected cases of locally recurrent NPC. The operation is associated with minor long-term complications and better quality of life. Early oncological results in are also encouraging. With rapid development of medical robotic technologies, further research in the field should be continued.