Prognostic Role of Porphyromonas Gingivalis in Oral Cavity Squamous Cell Carcinoma Patients

Background: Oral microbial species play direct and/or indirect role in carcinogenesis of oral cavity squamous cell carcinoma (OSCC). Porphyromonas gingivalis (Pg) has been identified a correlation with OSCC. Fimbriae play a vital role for its attribution of initial attachment and adhesion of Pg. Six genotypes (types I-V, Ib) of fimA were identified based on sequence variations and the genotype was suggested a relationship to pathogenicity of Pg.Objective: To investigate the abundance of Pg in OSCC as well as the frequency of Pg fimA genotypes in OSCC patients.Methods: Ninety-five OSCC patients and thirty-nine gender- and age-matched non-OSCC subjects were investigated abundance of Pg in saliva. Presence of Pg was compared in OSCC tissue and para-cancerous tissue from patient as well. Clinical data were extracted and patients followed up for a mean period of 13 months. Presence of Pg and fimA genotypes were investigated in OSCC tissue and in saliva, then PCR products were sequencing and compared.Results: OSCC patients showed high abundance of Pg in saliva (Chi-square=14.531, P=0.001). OSCC tissue showed strong in situ expression of Pg by in situ hybridization compared with normal tissue adjacent to OSCC. Patients with overabundance of Pg in saliva are associated with systemic disease (Chi-square=10.328, P=0.029), longer disease-free time (Z=-2.988, P=0.003), and lower recurrence rate (Chi-square=5.670, P=0.017). The abundance of Pg was an independent favorable prognostic factor (HR: 0.124, 95%CI: 0.016 to 0.941). There was dominant distribution of Pg with genotype I+Ib (21.1%), II (31.6%) and IV (21.1%) in OSCC patients. The fimA genotypes detected in saliva were in accordance with those in OSCC tissue, and there was significantly correlation in amplified Pg fragments similarity between in saliva and in OSCC tissue. Conclusions: This study indicated that Pg might involve in the pathogenesis of OSCC, and Pg might consider as a potential prognostic indicator in OSCC. There was a dominant distribution of Pg with genotypes I, Ib, II and IV in OSCC patients. The presence of Pg in tumor might be saliva in provenance.