Oral squamous cell carcinoma (OSCC) is the sixth most common malignancy globally with a 5 year survival rate of only 50% and one of the highest mortality rates of all cancers. Early detection and intervention are the most effective methods for improving patient prognosis and is based on the concept of clinically identifiable oral potentially malignant disorders (OPMDs) preceding malignancy. Early detection and treatment of OPMDs is hindered by the clinical subtlety associated with these lesions. This has driven the development of new technologies designed to aid clinicians in detecting OPMDs with high sensitivity and specificity to improve the prognosis of these lesions.
Identafi™ is a commercially available multi-spectral adjunctive screening device featuring three different lights which are used sequentially to examine oral tissues. In addition to a light emitting diode (LED) white light, the device also includes violet light of 405 nm wavelength and a 545 nm wavelength green-amber light. The violet and green-amber lights induce tissue fluorescence and reflectance spectroscopy respectively.
This thesis has been divided into two discrete but related experimental chapters evaluating the efficacy of Identafi™ in different clinical settings.
The first experimental chapter aims to address the lack of published studies evaluating oral mucosal health of the Australian Indigenous community in a prospective fashion in addition to assessing an adjunctive technique for detection of oral mucosal pathology in an urban Indigenous community. The Identafi™ was compared to a conventional oral examination (COE) using an extra-oral incandescent light source. The urban Indigenous community did not display a significantly higher prevalence of risk factors such as smoking and alcohol consumption when compared to their non-Indigenous counterparts living in the same region, nor were they more likely to have oral mucosal lesions. The Identafi™ white and violet lights were capable of highlighting new lesions not seen during COE. Diffuse vasculature was only noted in 15 cases.
The second experimental chapter evaluated the efficacy of all three light functions in visualising and detecting OPMDs in a private specialist clinic. The Identafi™ was compared to COE conducted using LED white light illumination in conjunction with 2.5x magnification loupes. The Identafi™ white light produced lesion visibility and border distinctness equivalent to that provided by an overhead white light and 2.5x magnification. The violet light provided assessment of tissue autofluorescence in a comparable manner to VELScopeTM, another autofluorescence imaging system. LAF and diascopic fluorescence were significantly associated with clinical diagnosis but could not predictably and constantly differentiate OPMDs from benign lesions, as LAF was noted in both lesion types.
Clinically visible vasculature was significantly associated with lesion features and clinical diagnosis but was only noted in 40.5% of cases. Lesions with keratotic features or a homogenous clinical appearance were less likely to display clinically visible vasculature. The presence of diffuse vasculature alone was not a predictable indicator of underlying mucosal pathology as vasculature of this type was noted in OSCCs, oral lichen planus and benign keratosis. Furthermore, lesions which were not detected using the violet light, or displayed retained fluorescence (RF), were also more likely to be undetected using the green-amber light.
These studies demonstrate that use of Identafi™ is technique sensitive and requires a high level of clinical skill. While the intra-oral white light displays significant clinical utility, care must be taken when interpreting the findings of violet and green-amber light examinations.