Impact of TLR9 and TLR7 gene polymorphisms on prognosis and survival of patients with oral squamous cell carcinoma

Despite significant efforts in developing new diagnostic and therapeutic modalities, oral squamous cell carcinomas (OSCCs) still exhibit a high recurrence rate, a low five-year survival rate, and an increasing prevalence. Toll-like receptors (TLRs), which initiate and perpetuate immune mechanisms upon activation, have been linked to immune surveillance and the antitumor immune response. The aim of this study was to investigate the association between the polymorphisms of the TLR7 rs3853839 and TLR9 rs187084 genes and OSCC risk, clinicopathological features, and survival. Genotyping was assessed by real-time polymerase chain reaction (PCR) in 95 HPV-negative OSCC patients and 107 age- and sex-matched healthy controls. Patients with lymph node metastases had higher frequencies of the TLR9 rs187084 CC variant genotype compared to the major TT genotype (P = 0.020) and to T-allele carriers (combined TT + CT genotypes, P = 0.015). A higher prevalence of advanced stage III was observed in patients with the TLR9 rs187084 variant CC genotype compared to TT (P = 0.047) and to T-allele carriers (TT + CT, P = 0.037). Kaplan-Meier analysis revealed a lower overall survival (OS) rate in patients with the TLR9 rs187084 variant CC genotype compared to the TT genotype (P = 0.010, log-rank test) and to T-allele carriers (TT + CT genotypes, P = 0.002), though it was not an independent predictor of OS. Both TLR9 rs187084 and TLR7 rs3853839 polymorphisms were associated with high alcohol consumption (P = 0.027 and P = 0.001, respectively). The investigated genetic variations were not associated with OSCC susceptibility. The variant CC genotype of the TLR9 rs187084 polymorphism might be a marker of poor survival and tumor progression in OSCC.