The Role of Porphyromonas gingivalis in Oral Carcinogenesis and Progression by Remodelling the Tumour Microenvironment: A Narrative Review

(1) Background: Oral squamous cell carcinoma (OSCC) is the most common type of head and neck malignancy worldwide. Despite the prevalence of modern diagnostic and prognostic techniques, late diagnosis and resistance to treatment still result in a low 5-year survival rate, high recurrence rate, and frequent malignant metastases. Increasing evidence indicates that bacteria of the oral microbiome, such as the Gram-negative anaerobic Porphyromonas gingivalis, may play a crucial role in the initiation and development of OSCC by inducing periodontitis. Indeed, epithelial-to-mesenchymal transition (EMT) and dysregulated immune response have been attributed to the activity of a dysbiotic microbiota. This comprehensive review examines the influence of P. gingivalis on oral carcinogenesis and progression, which has been associated with tumour microenvironment remodelling and the dysregulation of key signalling pathways related to epithelial-to-mesenchymal transition (EMT), cell-cycling, autophagy, and apoptosis. (2) Methods: The article reviews current literature on the possible role of P. gingivalis and induced dysbiosis, periodontitis and a pro-inflammatory environment as key mechanisms driving neoplastic epithelial changes and chemoresistance to anticancer agents in patients with OSCC; the research corpus was acquired from the Pub-Med/Medline/EMBASE/Cochrane Library databases. (3) Results: The identification of virulence factors and key mechanisms used by P. gingivalis to promote the development and progression of OSCC may support traditional diagnostic methods and factors related to treatment response and prevention of OSCC. (4) Conclusions: Emerging evidence suggests a possible association between periodontal bacteria and oral carcinogenesis. P. gingivalis may be an important potential target for future strategies aimed at treating oral cancer.