A set of optical techniques for improving the diagnosis of early upper aerodigestive tract cancer

Introduction: Early diagnosis of cancer of the upper aerodigestive tract (UADT) and its precursors may greatly improve the prognosis of the patients concerned. It seems possible that this goal can be reached using a combination of non-invasive optical methods. Materials and methods: In groups of patients (n=15-80) with, or at a high risk of developing, a malignant lesion of the UADT, different optical methods were investigated: autofluorescence imaging (AFI; n=80) and enhanced fluorescence imaging (EFI; n=79) using 5-aminolevulinic acid (5-ALA)-induced protoporphyrin IX (PpIX) as tools for optical screening; multiple fluorophore analysis (MFA; n=18) and elastic scattering spectroscopy (ESS; n=25) as optical biopsy methods; and optical coherence tomography (OCT; n=15) as a method to investigate the depth of a lesion (i.e. to differentiate dysplasia from early invasive cancer). Results: Using AFI or EFI in combination with conventional inspection, the detection of dysplastic/early malignant lesions was markedly improved (6 additional lesions for AFI vs. 7 for EFI). The lesions were furthermore easier to delimit from innocuous mucosa when applying fluorescence imaging. Both optical biopsy methods (MFA and ESS) proved able to differentiate between normal and cancerous mucosa (MFA: sensitivity 100%/specificity 94.4%; ESS: sensitivity 70.0%/specificity 78.8%). Using OCT, it was possible to clearly identify epithelial layers, basal membranes and superior lamina propria and disruptions within these in all patients examined. Conclusions: Even though so far the results are based on a very limited number of patients, the optical diagnostic methods investigated appear to be helpful for the detection, differentiation and mapping of early mucosal lesions of the UADT. Especially when used in combination with one another, they show great promise for improving early tumor diagnosis to the point that invasive measures such as diagnostic biopsies may well become redundant. © 2008 Elsevier GmbH. All rights reserved.