Discussion
The role of oesophagoscopy in HNSCC had been debatable in the
literature. Amongst North American studies, the rate of synchronous
malignancies in oesophagus ranged from 0-8% in most studies in the
1980s. However, in a review by Mcgarey et al14, there
had not been a single synchronous oesophagealmalignancy detected on
staging oesophagoscopy for patients with HNSCC since 2000 in North
American studies. In contrast, most studies fromTaiwan and Hong Kong
however had found significant rates of synchronous
oesophagealmalignancies among patients with HNSCCs. Chow et
al15 reported a rate of 10% for clinically important
oesophageal lesions found among 118 HNSCC patients undergoing
oesophagoscopy for workup. Chung et al6 and Huang et
al16 reported 23.3% and 14.8% synchronous
oesophagealmalignancies among patients with HNSCCs respectively in their
studies. These findings could be explained by the relatively higher
prevalence rate of oesophagealmalignancies in Asia17and the high prevalence of habits of chewing betel nuts in
Taiwan16,18, which is a common carcinogen for both
oesophagealmalignancies and HNSCCs.
In our study, the rate of occurrence of
synchronousoesophagealmalignancies was 5.8% (41/702) and out of these
41 lesions, 14 of them were onlydetectable by oesophagoscopy, i.e. these
malignancies would be otherwise missed by other means of investigation
(e.g. CT/PET-CT). 4 of these 14 patients were asymptomatic. In addition,
most of these malignancies (13/14) found were of early stage (stage 1
cancers). The overall survival and disease-free survival of patients
with malignancies exclusively detectable with oesophagoscopy were
significantly better when comparing with other
synchronousoesophagealmalignancies not exclusively detectable with
oesophagoscopy (P = 0.028).This had highlighted the importance of
staging oesophagoscopy in screening out synchronous
oesophagealmalignancies. It is also effective in screening out early
stage disease and potentially benefit patient’s survival.
Inour study, the risk factors associated with development of
synchronousoesophagealmalignancies included male gender, smoker/drinker
status and primary hypopharyngeal cancer.Anatomically, the hypopharynx
and oesophagus are structures connected continuously and there had been
proven association between malignancies from both
structures16,18-21. Huang et al16evaluated 248 patients with hypopharyngeal cancers prospectively and
reported a rate of 14.8% of synchronous oesophageal cancers and 9.4%
of oesophageal dysplasia among the patients. The French ENT society
concluded in their 2012 guideline that oesophagoscopy was indicated as
staging procedure for patients with hypopharyngeal
cancers22.
As the field cancerization theory2 suggested, alcohol
consumption and tobacco use are risk factors for development of
synchronous malignancies in the upper aerodigestive tract. Lower rates
of synchronous malignancy development among non-smokers or non-drinkers
was found in studies23,24. Alcohol drinking was
reported to be associated with increased risk of oesophagealmalignancy
in a study for patients with HNSCCs6 (OR:5.90, P =
0.020), as well as an independent risk factor for development of
oesophagealcancerous or dysplastic lesions in hypopharyngeal cancer
patients16 (OR: 6.95, P<0.05). The French
ENT society suggested that oesophagoscopy should be indicated for
patients with chronic alcohol intoxication as it increased the risk of
development of synchronous oesophagealmalignancies22.
Bronchoscopy had been less utilized as a routine screening procedure for
synchronous lung malignancies in patients with HNSCC when comparing with
oesophagoscopy. This could be due to the availability of other
non-invasive means of screening modalities such as chest x-ray, CT scan
of the thorax and PET-CT imaging. There was also a low yield of
bronchoscopy in the literature as a screening modality for HNSCC
patients, ranging from 0-1%21. In our study, the rate
of synchronouslung malignancies was at 0.6%, comparable with the
literature. Amongst them, non-of them is exclusively detectable with
bronchoscopy and all of them can be detectable on PET-CT, suggesting
that bronchoscopy can be potentially replaced by other investigative
modalities.