An investigation into the diagnosis, prediction and management of oral potentially malignant disorders

PhD ThesisOral cancer may be proceeded by dysplastic PMDs mainly presenting as leukoplakia or erythroplakia and which can carry an increased risk of malignant transformation. Therefore, early recognition of PMDs with a high potential for cancer development is important to improve patient outcome. 100 patients with dysplastic PMDs presenting in Newcastle underwent a standardised interventional management protocol based on risk factor assessment, laser excision of dysplastic lesions and long-term clinical follow-up at regular intervals. This patient cohort was studied in detail to examine the clinicopathological features that may influence disease progression. Single dysplastic PMDs were mainly observed in the floor of mouth, with 92% presenting as leukoplakia and 8% as erythroplakia. Follow-up revealed that 62% of patients remained disease-free following laser surgery, 17% showed recurrent-disease, 14% new-site dysplasia, with 5% malignant transformation and 2% developed OSCC at a site distant from the primary dysplasia. Clinical appearance, high grade dysplasia, larger sized PMDs, high risk sites and positive excision margins were shown to increase the risk of unfavourable clinical outcome. Malignant transformation was mainly seen in non-smokers and non-alcohol users, whilst new-site OSCC was only seen in non-smokers and light drinkers. The use of Raman spectroscopy in the detection and classification of dysplasia within the human oral tissue was investigated. Currently, histopathology is considered the diagnostic gold standard. Consensus opinion on dysplasia grading of individual PMD lesions using two classification systems (WHO and binary grading) was obtained and a spectral diagnostic model then correlated with the results. The ability of Raman spectroscopy to differentiate between dysplasia and morphologically normal tissue was shown, with an 81% sensitivity and specificity. This supports the suitability of the Raman system in clinical use to distinguish morphologically normal from dysplastic tissue. This work has also shown the efficacy of Raman spectroscopy in identifying early biochemical changes in epithelial dysplastic tissue before morphological/histological change becomes apparent.Ministry of Higher Education and Scientific Research in Republic of Ira