The Role of Oral Yeasts in the Development and Progression of Oral Squamous Cell Carcinoma: A Scoping Review

Abstract

The role of oral yeasts in oral squamous cell carcinoma (OSCC) has gained attention due to evidence linking fungal dysbiosis to carcinogenesis. While Candida albicans has been the primary focus, emerging studies highlight the importance of non-Candida species yeast genera. This scoping review synthesises the evidence on the role of oral yeasts, including Candida spp. and non-Candida species, in the development and progression of OSCC. A PRISMA-ScR-guided search was conducted in Medline, Embase, EBM Reviews, and CINAHL. Observational and experimental studies involving humans with OSCC, oral potentially malignant disorders (OPMDs), or oral epithelial dysplasia (OED) were included. This review analysed 75 studies. Research on oral yeast in OSCC has progressed since the 1970s, with advancements in identification techniques-from conventional culture methods to metagenomic sequencing and multi-omics approaches-alongside improved animal and cellular models of OSCC. These methodological advancements have identified notable distinctions in the oral mycobiome between carcinomatous and healthy states. Clinical findings reinforce the hypothesis that oral yeasts, particularly Candida spp., actively contribute to the dysplasia-carcinoma sequence. Emerging evidence suggests that oral yeasts may significantly modulate events contributing to OSCC progression. However, further mechanistic studies and robust clinical evidence are essential to establish causality and clarify their role in OSCC.

Keywords: Candida spp.; oral medicine; oral microbiome; oral potentially malignant disorders; oral squamous cell carcinoma; oral yeasts.

Figure 1

PRISMA-ScR search flowchart.

Figure 2

Geographical and temporal distribution of studies on oral yeast in OSCC. The map (top) illustrates the geographical distribution of studies, highlighting India as the leading contributor, followed by other regions such as Europe, North America, South America, and the Asia–Pacific. The graph (bottom) depicts the temporal distribution of studies, showing a gradual increase in publications from the 1970s to the 2020s, with a significant rise in recent years.

Figure 3

Techniques used for oral yeast identification (left) and speciation (right) across studies. Culture- and histologic-based methods dominate identification, while phenotype-based and PCR-based approaches are most common for speciation.