Introduction: Oral cancer and potentially malignant disorders (PMD) are associated with classic risk factors such as tobacco and alcohol consumption, and with emerging factors such as yerba mate consumption. The oral microbiota has emerged as a potential modulator of the tumor microenvironment, chronic inflammation, and carcinogenesis. Several studies suggest that microbiota dysbiosis could contribute to the progression of oral lesions through pro-inflammatory and immunomodulatory mechanisms. However, few studies compare the oral microbiological profile among benign lesions, primary hyperplastic tumors (PHTs), and squamous cell carcinoma (SCC), considering different sample types and dietary habits. Objective: To evaluate the oral microbiological composition and its association with risk factors, in order to identify microbial profiles potentially useful as biomarkers of long-term tumor risk and progression. Methods: A descriptive observational case-control study was conducted. Forty-seven patients were included, distributed into three clinical groups: control (reactive hyperplastic tumors, n = 24), PMD (n = 17), and SCC (n = 6). Samples of healthy mucosa and lesions were obtained using exfoliative cytology, as well as saliva samples. The presence of Candida spp., Lactobacillus spp., Staphylococcus aureus, Staphylococcus spp., Escherichia coli, and other Enterobacteriaceae was evaluated using cultures on specific selective media. History of tobacco, alcohol, and yerba mate consumption was recorded. Results were expressed as detection frequency. Statistical analysis: Fisher's exact test was used, and odds ratios (OR) with 95% confidence intervals were estimated. Results: Statistically significant associations were observed between sample type and the frequency of certain microorganisms. Candida spp. showed a differential distribution among sampling sites (healthy mucosa, lesion, and saliva), with a higher proportion in saliva (p = 0.028). Staphylococcus aureus showed significant differences according to sample type (p = 0.033), being more frequent in saliva. Staphylococcus spp. showed significant variation among sample types, with a higher frequency in saliva (p = 0.0066). Risk factor analysis: Tobacco use was significantly associated with a higher frequency of Staphylococcus aureus detection (OR = 3.39; 95% CI: 1.40–8.68; p = 0.004). Alcohol consumption showed statistically significant associations with two bacterial groups: a higher probability of Staphylococcus aureus detection (OR = 9.53; 95% CI: 3.27–34.29; p < 0.001) and a lower frequency of Staphylococcus spp. (OR = 0.25; 95% CI: 0.11–0.54; p < 0.001). No statistically significant associations were observed between yerba mate consumption and the microorganisms evaluated (p > 0.05). When stratified by clinical group, these associations remained significant mainly in the control group, and in the case of Staphylococcus spp., also in the SCC group. Conclusion: The results show significant associations between the type of oral sample and the presence of certain microorganisms. While alcohol and tobacco significantly alter the oral microbial profile towards a pro-oncogenic environment, yerba mate consumption showed no influence. This reinforces the potential of the microbiota as a strategic biomarker in detecting changes associated with carcinogenesis.

Oral cancer (2) and potentially malignant disorders (1, 3 y 4)