Detection of epidermoid squamous-cell carcinoma by laser induced autofluorescence -preliminary results

Abstract

Epidermoid squamous-cell carcinoma is by far the most common malignant tumor of larynx (95-96%), representing 1.6-2% of cancers in men and 0.2-0.4% of malignancies in females, with a world growing incidence and a slight dominance in urban areas. By exposing cells and tissues to UV light, the excitation of naturally occurring chromophores occurs in part by non-radiative deactivations, in part via fluorescence emission. Using laser induced autofluorescence (LIAF) in natural tissues not impregnated with photosensitizers as a noninvasive autofluorescence technique for both diagnosis and intraoperative assessments of laryngeal cancer we can improve the tumor malign identification in vivo. A total of three laryngeal biopsies (i.e. three pairs of tissues, each pair containing a healthy and a tumor tissue sample extracted from the same patient) were considered in this study. The samples were collected from patients previously diagnosed with stage T3 laryngeal carcinoma. Immediately after the surgery fragments of normal tissue and neoplastic tissue were collected, fragments of which later, after freezing, were sectioned in 25-30 μm thickness slices and stretched to quartz slides. All samples were subjected to controlled laser irradiation using a pulsed diode laser (λ=375nm, pulse width=87ps, frequency 31MHz) and the autofluorescence and its lifetime were collected using two optical fibers (inner diameter 400µm and 1500µm, respectively) positioned in a 45 o geometry. The signals were recorded using a spectrograph and a photo-sensor module, the output of which was fed to a digital oscilloscope. We assessed the impact of laser induced autofluorescence and autofluorescence lifetime measurements in order to identify the differences between healthy and tumoral laryngeal tissue and outlining them, in terms of differences between the laser autoinduced fluorescence averaged intensity. The results determined the usefulness of laser induced spectroscopy in the diagnosis of laryngeal squamous cell carcinoma, discriminating between the malignant and normal tissue by analyzing the differences in spectral autofluorescence intensity and autofluorescence lifetime. Acknowledgements: This work has been financed by the National Authority for Research and Innovation in the frame of Nucleus programme -contract 4N/2016 and the project number PN-II-ID-PCE-2011-3-0922. The authors thank Prof. M. L. Pascu for permanent support in performing this research.