Early Detection of Superficial Nasopharyngeal Carcinoma by Narrow Band Imaging: a Randomized Controlled Trial

Nasopharyngeal carcinoma (NPC) is a common cancer in Southeast Asia. It typically affects middle-aged people and is commonly diagnosed in the late stage because of its deep location and vague symptoms, and this late diagnosis leads to decreased survival. Unfortunately, most of the NPC patients we encountered had Stage III or IV disease. Although NPC is radiosensitive, 25% of NPC patients still suffer from local relapse in Taiwan, and tumor recurrence also leads to a poor prognosis. Therefore, early diagnosis of newly diagnosed or recurrent NPC is important to define appropriate therapeutic strategies. Narrow-band imaging (NBI) is a novel optical technique that enhances the diagnostic sensitivity of endoscopy for characterizing tissues by using narrow-bandwidth filters in a sequential red-green-blue illumination system. The narrowband blue light, which has a short wavelength (415 nm), penetrates the mucosa and highlights the superficial vasculature. Thus, superficial mucosal lesions that cannot usually be detected by regular white-light (WL) endoscopy can be identified on the basis of their neoangiogenetic vasculature pattern by using blue light in NBI. In our pilot study, we successfully detect newly diagnosed early NPC by irregular microvascular pattern or side-difference, and early recurrent NPC by irregularities signs in NBI closer view. Many studies showed that the detection of plasma Epstein-Barr virus (EBV) DNA might be helpful to screen newly diagnosed NPC and monitor recurrence/treatment outcome of NPC post-irradiation. On the other hand, NPC might be early detected during dysplastic stage by NBI in our previous study. However, the diagnostic yield of NBI in the early detection of superficial NPC and diagnostic accuracy between NBI and plasma EBV DNA has not been investigated. Therefore, we conducted a prospective randomized controlled study to directly compare WL and NBI in the early diagnosis of NPC among high-risk patients (post-treatment NPC in a state of remission, family history of NPC or higher plasma EBV titer, unknown origin of neck mass and epistaxis). 320 patients with high-risk were randomly assigned to primary WL followed by NBI (n = 160) or primary NBI followed by WL (n = 160) in a back-to-back fashion. Regular endoscopy examination and plasma EBV DNA assay were scheduled every 3 to 6 months for these high risk populations. The primary aim was to compare the real-time detection rates of superficial NPC between WL and NBI. The secondary aim was to evaluate the diagnostic accuracy of these techniques. The third aim was to compare the diagnostic accuracy of early NPC between NBI and plasma EBV DNA. Upon completion of this study, we will understand the definite clinical value of NBI for early NPC and the difference between NBI and plasma EBV DNA for high risk patients in Taiwan.

Project ID:PC10108-0685
External Project ID:NSC101-2314-B281-008