Real-time in vivo cancer staging of nasopharyngeal carcinoma patients with rapid fiberoptic Raman endoscopy

Cancer staging is important to guide treatment and for prognostication. This work aims to demonstrate the ability of rapid fiberoptic Raman endoscopy for real-time in vivo cancer staging of nasopharyngeal cancer (NPC) patients. We interrogate 278 tissue sites on the primary NPC with different cancer stages from 61 NPC patients and 50 healthy volunteers using rapid fiberoptic Raman endoscopy examination. Distinct Raman spectral differences of NPC at different cancer stages are observed through simultaneous fingerprint and high-wavenumber (FP/HW) Raman spectral measurements, reflecting the biomolecular differences of NPC tumor across various cancer stages. Raman staging model is established based on in vivo FP/HW tissue Raman spectra together with partial-least-squares linear-discriminant-analysis (PLS-LDA) and leave-one-tissue-site-out cross-validation (LOOCV). In vivo FP/HW Raman endoscopy provides an overall diagnostic accuracy of 92.81% for identifying different stages of NPC (i.e., NPC stage I&II and NPC stage III&IV) from normal nasopharynx. Specifically, the diagnostic sensitivity of 91.18% is obtained for identifying NPC stage I& II; and the sensitivity of 93.04% is achieved for classifying NPC stage III&IV from normal tissue. The key tissue biomolecular variations responsible for different NPC stages have been identified using biomolecular Raman modeling developed based on non-negative linear regression. The essential biomolecules (chondroitin sulfate, glucose, hemoglobin, oleic acid and triolein) are uncovered from the Raman spectra of NPC tissues through biomolecular modeling with significant variations (p < 0.05) between early-stage NPC (stage I and stage II) and late-stage NPC patients (stage III and stage IV). Our pivotal work demonstrates for the first time that fiberoptic Raman endoscopy is a robust analytical tool for real-time in vivo NPC staging in clinical settings.