OP119: Molecular based in vivo optical imaging for detection of oral carcinogenesis

Abstract

Purpose Envision of tissue change during carcinogenesis has evolved in recent years. From a clinical standpoint, the new paradigms tend to shift from the clinically identifiable lesion per si, to other parameters such as “field” changes involving genetically and epigenetically altered cells within a tissue. Materials and methods A review of the literature shows that genetically altered fields of cells are not always clinically or histologically evident and may represent, even if clinically unremarkable, a significant risk towards carcinogenic changes, with some studies showing that new imaging tools may improve our ability to clinically distinguish normal from premalignant and malignant oral tissue in a real-time fashion, with some complementary lesion-focused assessments being accepted by some health authorities. Results Fluorophores are specific tissue compounds that may be excited by higher-energy light so that they re-emit lower-energy light, thus making up the autofluorescence image of the tissue. Changes in fluorescence reflect a complex interplay of alterations to fluorophores in tissue and structural changes in tissue morphology. The endogenous fluorophores most relevant to optical screening and diagnosis of precancer and cancer are those that excite in the spectrum from visible violet/blue (400–450 nm) to UV-A (315–400 nm) and have properties that have been spectroscopically correlated with disease progression. Direct fluorescence visualization (FV) is currently available for widespread use in the oral cavity. However, this method is still a matter of controversy regarding its poor specificity because of confounding benign conditions, including inflammation. Discussion Selection of an optimum wavelength that may differentiate between oral cancers or premalignant lesions and confounders in a precise and objective manner remains of the utmost importance. Optical imaging technologies (e.g., in vivo confocal microscopy, molecular targeted optical contrast agents alone and in combination) must be integrated in the future with molecular findings to further advance our understanding of disease processes. Conclusion Molecular abnormalities have traditionally only been identified in resected tissue. Definition of the biomarkers which reliably indicate malignant potential and testing optical imaging measurements against these markers may lead to enhanced optical imaging that enable real-time, in vivo delineation of molecularly damaged mucosa.