4 DISCUSSION
Oncologic outcomes after TORS in oropharynx cancer are generally favorable. Also, despite initial concerns about the imperfection of en bloc resection, TORS is recognized by many researchers as a relatively safe technique. In a systematic review involving 12 TORS studies with 772 patients, adverse events of TORS were hemorrhage (2.4%), fistula (2.5%), and placement of gastrostomy tubes at the time of surgery (1.4%), although the need for gastrostomy tubes increased to 30% of patients during adjuvant treatment.23 A study that analyzed data from 305 patients from the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) datasets showed a low, 7.9%, complication rate and a 0.7% 1-month mortality rate.24
There were no severe complications or mortality in this study, but there were some minor complications such as minor hematoma and seroma. Also, no procedure was interrupted or converted to conventional radical surgery because the tumor could not be removed during TORS.
Several studies reported that the temporary tracheostomy rate was from 0 to 31% (less than 10% in most studies) and the permanent tracheostomy rate was 0-2%.9,15,16,18 In this study, temporary tracheostomy was performed on six patients during TORS. However, none of these patients required permanent tracheostomy.
Functional outcomes are essential, particularly in HPV-related oropharyngeal cancer, because this cancer occurs in relatively younger patients who respond well to both surgical and non-surgical treatment modalities and show good prognoses. Therefore, post-treatment morbidity, such as xerostomia and dysphagia, can be a life-long problem in these patients. From a functional outcome point of view, primary TORS can be an excellent alternative to concurrent chemoradiation therapy.7
To evaluate speech-related function, we used the Korean Speech Mechanism Screening Test, a functional scale specially designed for use in Korea. The test has been validated in the normal Korean population and includes tests for tongue mobility, maximal phonation time, verbal diadochokinesis, articulation, and reading speed. In this study, long-term functional speech outcomes were acceptable and comparable to those of normal subjects. All speech parameters, including tongue mobility, maximal phonation time, verbal diadochokinesis, articulation, and reading speed, were not different from those of the normal population.
Some previous papers also reported favorable speech function after TORS for oropharyngeal cancer as measured by other methods. For example, a study conducted by Moore et al. revealed that all 45 patients who underwent TORS for oropharyngeal cancer showed normal speech function at four weeks postoperatively. In that study, speech was assessed as normal, having minor dysphonia, or having gross dysphonia. However, 4 of that study’s patients had rhinolalia when discharged from the hospital.15 Dziegielewski et al. also reported speech function was not different from the preoperative baseline in 76 patients 12 months postoperatively when assessed using a health-related quality of life questionnaire.11
To analyze swallowing outcomes after TORS, various methods, such as feeding tube rate, fiberoptic endoscopic evaluation, MBS, and swallowing-related quality of life, were used in previous studies. Swallowing function usually declines in immediate postoperative periods and is restored within several weeks.10,14,15,23 In addition, postoperative swallowing outcome is related with preoperative function, T-classification, nodal status, location of primary tumors, and need for adjuvant chemoradiation.15
The perioperative feeding tube rate in TORS varies from 3% to 100% but is relatively lower than that when using non-surgical therapy (29% to 60%).10,14,15 Sinclair et al. reported that ten out of 42 primary TORS patients with cancer of the oropharynx required gastrostomy tubes. However, this rate improved over time, even after 12 months, and no one required a PEG tube by the commencement of radiation therapy.18 Chronic PEG tube dependence was reported to be from 0 to 7%.14 Sharma et al. reported that stage-matched patients undergoing TORS for oropharyngeal cancer had lower PEG tube dependency compared to patients undergoing non-surgical therapy (33.3% vs. 84.1%), although the PEG tube prevalence decreased over time in both TORS and non-surgical groups.17 In this study, only 1 patient (2.4%) was dependent on a PEG tube at 36 months of follow-up.
In this study, we objectively evaluated swallowing outcomes using MBS. The MBS test was performed in 32 out of 41 patients. Most patients showed favorable swallowing outcome in this study, although there were minor impairments in some patients. No prior research has evaluated swallowing outcome after TORS using MBS. Most previous studies were based on questionnaires, including the University of Washington Quality of Life Questionnaire,12 the EAT-10,13 and the MD Anderson Dysphagia Inventory.18 In a study comparing 92 patients with early-stage oropharyngeal cancer treated with TORS with/without adjuvant therapy and 46 patients treated with definitive chemoradiation therapy, the two groups showed similar locoregional control rate, overall survival, and disease-free survival. However, the TORS group had a significantly better saliva-related quality of life than the definitive chemoradiation therapy group until 24 months after treatment.12 Achim et al. also reported an adverse effect of adjuvant therapy on swallowing. This group showed that the TORS-only group showed faster restoration of swallowing and less weight loss in the long-term than the TORS with radiation or chemoradiation therapy group.13 However, generally, swallowing function and health-related quality of life deteriorate in the immediate postoperative stage and then gradually recover after TORS regardless of the need for adjuvant therapy.13,18