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