Photo-Detection And Photo-Destruction Of Oral Neoplasia In An Animal Model

17025 Background: Optical techniques for non-invasive early detection, mapping and eradication of oral premalignant lesions (OPLs) and oral squamous cell carcinoma (OSCC) offer many advantages that may benefit patients greatly. Our objective was to assess the utility of photodynamic diagnosis and therapy using toluidine blue (TBO) and light at 633nm for early detection, mapping and selective phtodestruction of neoplastic oral tissues in the hamster cheek pouch carcinogenesis model. Methods: DMBA carcinogenesis was applied to one cheek pouch in 20 hamsters for 6 weeks. After topical application of acetic acid is (1%) and TBO (0.5%), cheek pouches were irradiated using previously identified parameters: 15 J/cm2, 30 J/cm2, 45 J/cm2, and exposure duration of 3 min, 6 min, 9 min and 12 min. After laser irradiation, animals were sacrificed and cheek pouch tissues underwent routine histopathological preparation and evaluation. Using (a) TBO flouorescence and (b) histopahtology, lesion presence was scored as yes/no and lesion delineation was mapped microscopically using a grid and IPLab™ software. Results: Areas of pathology were clearly identified by TBO fluorescence (k=0.85 for delineation). At all laser parameters tested, selective photodestruction was seen, as evidenced by intra-vascular thrombosis and neovascularization in the pathological tissues. Cellular thermal damage was evidenced by atypical cell membranes, vacuolization and loss of inter- and intracellular integrity in the areas of neoplasia. Maximal photodestruction with minimal thermal damage was observed at 30 J/cm2 after 9 min irradiation. Conclusions: Topical toluidine blue may be a useful tool for photodynamic diagnosis and for possible therapy of neoplasia in the oral mucosa No significant financial relationships to disclose.