Candida in oral pre-cancer and oral cancer
Introduction
Oral cavity plays host to a wide array of microorganisms inclusive of variety of bacteria, viruses and fungi. This natural microflora is essential for the normal development of host physiology and contributes to host defenses by excluding exogenous microorganisms. Certain alterations in diet, medications, habits and host immune status may lead to overgrowth of minor components of oral microflora which can predispose the site to disease. Oral microbes can also act as an opportunistic pathogens and of particular relevance in this context is the infection caused by fungal organism most notably candida.
It is well known that Candida species are normal commensals of oral cavity in up to 50% of the healthy population [1]. In health, the commensal oral microflora may play an important role in preventing candidal overgrowth by inhibiting the adherence of yeasts to oral surface. Involvement of various local and systemic host factors may operate in vivo to facilitate the conversion of this harmless commensal to pathogenic organism.
Candidiasis is one of the common mycotic infections of the oral cavity which manifest in various forms. Of particular interest is chronic hyperplastic candidiasis which is sometimes referred to as candidal leukoplakia. The association of oral leukoplakia with candida was first reported by Cornea et al. (1965) and Jepsen and Winther (1965) and since then various hypothesis related to the role of candida in oral pre-neoplasia and neoplasia were widely discussed [2].
Reports indicate that leukoplakia harboring candidal hyphae constitute 7–50% of all leukoplakias [2]. Controversies surround the fact on whether the yeasts are causally involved in the development or transformation of leukoplakia or it is only a co-incidental finding.
Oral cancer is found to supervene in 9–40% of candidal leukoplakias compared with the 2–6% risk of malignant transformation for leukoplakias in general [3]. The risk of carcinoma developing in candidal leukoplakia will depend on whether the lesion is speckled or homogenous, the presence and the degree of epithelial dysplasia and the management adopted. Evidence indicate a heightened role for the Candida species in oral carcinogenesis based on the fact that certain species have higher nitrosation potential thereby elaborating nitrosamine compounds which plays a role in initiation of carcinogenesis. Literature also suggests a potential role of candida in promotion of carcinogenesis.
However, the exact role of candida in development of pre-malignancies and its progression to malignancies is of considerable debate which forms the basis of the present article.
Section snippets
Hypothesis
The authors suggest that nitrosation potential of the Candida albicans results in production of carcinogenic nitrosamine thus pre-disposing the oral epithelium to dysplastic changes leading o carcinoma. Further contributing factors include the integrity of the oral mucosa and tobacco smoking habits which might enhance the virulence of the organism. Though the direct role of C. albicans in oral squamous cell carcinoma is debatable, our hypothesis suggests that C. albicans in conjunction with
Discussion
Candidiasis is a common opportunistic infection of the oral cavity; the most common pathogen being C. albicans. C. albicans reside in the oral cavity as a normal commensal aided by a complex process involving factors related to yeast cells, host cells and environmental factors which contributes to the virulence of the organism. However interplay of various factors may pre-dispose to infection causing several clinical manifestations. A major virulent attribute of candida is its ability to invade
Future considerations
Although an association of candida and oral pre-cancer and cancer is evident from the literature, the exact causative role of the organism is far from being proved. This could be due to the nature of the C. albicans involved in the lesions and a variable ability of the organism as a causative agent according to the type of the strain. The variable effect could be due to the genotypic attributes of the colonizing yeasts which may be more virulent than their counterparts. Based on these findings,
Conflict of interest statement
None declared.
Acknowledgment
Authors wish to thank Dr. R. VenkataSubramanyam, Professor and Head, Department of Oral Pathology and Microbiology, for his encouragement, motivation and timely support in shaping up this study. Thank you Sir.
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