The value of flexible endoscopy with Narrow Band Imaging for the evaluation of recurrence of laryngeal and hypopharyngeal tumours after radiotherapy

Background: The dia­gnosis of recurrent upper aerodigestive tumours is difficult, especially in the case of previous curative radiotherapy (RT) or chemoradiotherapy (CRT). Progress in the dia­gnostics of head and neck cancer came with the development of optical endoscopic imaging methods. The aim of this study was to analyse the benefits of flexible Narrow Band Imaging (NBI) in the visualization of suspected recurrence of malignancy in patients after curative RT (CRT). Methods: A total of 58 examined patients in follow-up after curative RT or CRT for laryngeal and hypopharyngeal squamous cell carcinoma were enrolled in the study. All patients underwent transnasal flexible endoscopy in conventional white light and NBI in local anaesthesia. Changes in microvascular architecture (intraepithelial papillary capillary loops – IPCL) have been classified according to Ni. IPCL I–III were considered to be non-suspicious, and therefore no histopathological examination was indicated. IV and V type findings were verified using HDTV NBI intraoperatively with bio­psy sampling and subsequent histopathological correlation was performed. Results: Transnasal videoendoscopic examination with NBI revealed a suspicious finding (IPCL type IV and V) in 23/58 (39.7%) patients, non-suspicious finding (IPCL I–III) in 35/58 (60.3%). Histopathological examination verified the positive finding (precancerous or malignant changes) in 12/23 (52.2%) and negative finding in 11/23 (47.8%) cases. The sensitivity, specificity, positive and negative predictive value of flexible NBI endoscopy were 100%, 76.1%, 52.2% and 100% respectively. According to the Kappa index (K = 0.568), we proved a moderate concordance between flexible NBI endoscopy and histopathological results. Conclusions: Transnasal flexible endoscopy with NBI in outpatient settings contributes to an early detection of pathological changes also in post-radiation altered mucosa of the larynx and hypopharynx, while a correct interpretation of in NBI findings is required to reduce the incidence of false positive results. Keywords: squamous cell carcinoma – Larynx – radiotherapy – narrow band imaging – Ni classification – hypopharynx