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dc.contributor.advisorHussaini, Haizal
dc.contributor.advisorRich, Alison Mary
dc.contributor.authorDe Silva, Harsha Lal
dc.date.available2018-11-07T20:20:39Z
dc.date.copyright2018
dc.identifier.citationDe Silva, H. L. (2018). Does Candida albicans influence oral carcinogenesis? (Thesis, Doctor of Clinical Dentistry). University of Otago. Retrieved from http://hdl.handle.net/10523/8555en
dc.identifier.urihttp://hdl.handle.net/10523/8555
dc.description.abstractOral squamous cell carcinoma (OSCC) has a multifactorial aetiology. The advanced disease is associated with significant morbidity and mortality. Many OSCC are preceded by clinically apparent oral potentially malignant disorders (OPMD) providing a potential window for early diagnosis and intervention to achieve better clinical outcomes. Candida albicans is a common oral commensal but may turn pathogenic under certain conditions. An association between C. albicans and OPMD/OSCC has been claimed since the 1960s. Yet, there is no convincing evidence to incriminate the organism with a causative role in oral carcinogenesis. Aim of the study: To investigate the role of C. albicans colonization and infection in oral carcinogenesis using immunohistochemistry (IHC), histopathology and clinical information in patients with OPMD/OSCC. Study hypothesis: Presence of C. albicans colonization and infection will show a positive correlation with severity of oral epithelial dysplasia (OED) and expression of specific molecular markers when compared with lesions without the presence of C. albicans. Materials and methods: The study sample comprised formalin-fixed paraffin-embedded (FFPE) oral mucosal biopsy tissues of consecutive patients who presented for treatment of clinically suspicious OPMD/OSCC at a referral hospital in Sri Lanka. Clinical data collected included demographic, behavioural and health related information. The presence/absence of lesion surface colonization by C. albicans was determined by culturing material obtained from a scraping. Subsequently all lesions were biopsied and histopathologically examined to detect and record the presence/absence of Candida hyphae infiltration in the epithelium and for the presence/absence of low-risk OED, high-risk OED or OSCC. Clinical information was tabulated and statistically analysed to investigate whether presence/absence of C. albicans colonization was an independent risk factor for presence/absence of high-risk OED/OSCC. Immunohistochemistry was performed to assess p53 and Ki67 protein expression in 62 selected samples with either, C. albicans colonization and infection or without C. albicans colonization/infection. Results: The study sample (n=139) comprised 127 males (mean age 57.4 yrs.) and 12 females (mean age 63.6 yrs.). Betel-quid chewing was common (58.3%) followed by alcohol use (46.8%) and smoking tobacco (29.5%). Only 12.9% were denture wearers while 28.1% reported a medical condition indicative of potential immune compromise. Ninety-six (69.1%) patients had C. albicans colonization of which 28 (29.2%) showed Candida infection with hyphae invading the parakeratin layer of the epithelium. A highly significant independent association was observed between C. albicans colonization and OPMD having high-risk OED (p=0.00, RRR=4.92). Immunohistochemistry (n=62) showed marginally significant (p=0.08) increased mean immunoreactive score for anti-Ki67 in Candida-infected OPMD. There was significantly high immunopositivity for anti-Ki67 (p<0.01) and anti-p53 (p=0.01) evident in the maturation compartment of the epithelium in OPMD having Candida colonization and infection. Conclusions: C. albicans colonization in oral mucosal lesions had a significant independent association with occurrence of high-risk OED and OSCC. The presence of C. albicans colonization and infection is associated with increased cell proliferation and a significantly increased immunopositivity for anti-Ki67 and anti-p53 in the maturation compartment of the epithelium on OPMD. Taken in context, these findings support a potential causative role for C. albicans in oral carcinogenesis which merits further investigation and validation.
dc.language.isoen
dc.publisherUniversity of Otago
dc.rightsAll items in OUR Archive are provided for private study and research purposes and are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectCandida
dc.subjectalbicans
dc.subjectoral
dc.subjectcarcinogenesis
dc.titleDoes Candida albicans influence oral carcinogenesis?
dc.typeThesis
dc.date.updated2018-11-07T05:14:54Z
dc.language.rfc3066en
thesis.degree.disciplineOral Diagnostics and Surgical Sciences
thesis.degree.nameDoctor of Clinical Dentistry
thesis.degree.grantorUniversity of Otago
thesis.degree.levelDoctoral
otago.interloanyes
otago.openaccessAbstract Only
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