Are Probiotics Helpful If There Is a Dysbiotic Microbiome Involved in Oral Squamous Cell Carcinoma?

The oral cavity hosts the second most diverse microbial community. All inflammatory diseases of the oral cavity typically have a polymicrobial origin. Modern epidemiological and metagenomic evidence shows significant associations between potential periodontal pathogens, periodontitis, and oral cancer. Notably, Fusobacterium nucleatum and Porphyromonas gingivalis have been shown to promote carcinogenesis in mechanistic studies. Probiotics aim to modulate the normal inhabitants of a healthy oral biofilm, preventing the elevation of pathogenic microorganisms (pathobiont). Besides competing for attachment sites and host-derived nutrients, these probiotic strains may also produce bacteriocins to combat pathobiont. Importantly, probiotic strains can modulate the host’s innate immune mechanisms and produce anti-inflammatory substances. However, the precise mechanisms by which probiotics help re-establishing a healthy oral biofilm remain under explored. There is inconsistency in the findings regarding the ability of probiotics to reverse dysbiotic microbiomes in oral cancer patients, although there are promising individual cases of success. Inter-individual variations are a significant factor contributing to these discrepancies. Since the prognosis for oral diseases depends on the specific microbiota and immune responses of each patient, the outcomes of probiotic therapy will also vary among individuals. Personalized treatment has been successful in traditional oral healthcare, and probiotic therapy should follow this trend, given the undeniable inter individual variation in the oral microbiome. Expanding combination therapies to include various probiotic bacterial strains and species could enhance our ability to address the diverse microbiomes in individuals, with a focus on prevention and control of oral squamous cell carcinomas (OSCC).