Limitations of the study
Our study has some limitations. First, although most patients with HPSCC
were referred for IEE screening from the Department of Otolaryngology,
the referral rate was not 100%. Some patients were referred from other
physicians when experienced the symptom of dysphagia. This bias may
increase the incidence of second primary ESCNs in patients with HPSCC.
Second, this was a retrospective study with a relatively small sample
size. Larger prospective studies are necessary to confirm the
effectiveness of IEE for early detection and treatment of second primary
ESCNs in patients with treated HPSCC.