Light-induced fluorescence spectroscopy: a potential diagnostic tool for oral neoplasia

For the early detection of oral neoplasia, light-induced fluorescence spectroscopy was used to measure the fluorescence emission of malignant (squamous cell carcinoma & verrucous carcinoma) and premalignant (epithelial dysplasia, hyperkeratosis & lichen planus) oral tissues as well as normal oral mucosa ex vivo to assess the ability of this technique to distinguish neoplastic from normal oral tissues. The emission spectra of histologically normal and neoplastic oral tissues were obtained under excitation wavelengths varied from 270 nm to 400 nm at 10-nm intervals. At 300-nm excitation, the most intensely fluorescent peak occurred at 330-nm and 470 nm emission. At 330-nm emission, the spectrum of the malignant oral tissue was significantly stronger than that of the normal oral mucosal tissue after area normalization. However, at 470-nm emission, the spectrum of the malignant oral tissue was significantly weaker than that of the normal oral mucosal tissue. A diagnostic algorithm based on the ratio of relative intensities of 330 nm to 470 nm emission within the +/-5 nm peak area of each sample was calculated and paired. The histogram of ratios showed that histologically neoplastic oral tissues could be distinguished from normal oral mucosal tissues using the 300 nm excitation wavelength. The average ratio of malignant or premalignant oral samples was significantly greater than that of the normal oral mucosal samples (p < 0.001). This ex vivo study indicated that fluorescence spectroscopy may be useful in differentiating malignant or premalignant oral tissue from normal oral mucosa.