Reduced Oral Squamous Cell Carcinoma Risk Associated with MLH1 rs63749795 Polymorphism in the Dominant Genetic Model

Background: Oral squamous cell carcinoma (OSCC) represents the predominant form of cancer affecting the oral cavity, accounting for more than 90% of all oral malignancies. Despite advancements in treatment, the five-year survival rate has remains relatively unchanged, primarily due to late-stage diagnosis. This study aimed to evaluate the genetic variation in MutL homolog 1 (MLH1) (rs63749795) in patients with OSCC. Methods : A cross-sectional case-control study was performed, including a total of 102 patients diagnosed with OSCC and 100 healthy individuals serving as controls. Genotyping of the MLH1 rs63749795 polymorphism was performed using tetra-primer amplification refractory mutation system-polymerase chain reaction (TP-ARMS-PCR) method, followed by agarose gel electrophoresis. Results : The predominant genotype observed in both OSCC patients and healthy controls was the CT genotype, with respective frequencies of 45.1% and 55%. The least frequent genotype in both groups was TT, with frequencies of 12.7% in patients and 17% in controls. Most patients were in tumor grade 1 (70.96%) and tumor stage III (35.8%). Among the patients, 53.3% showed lymph node involvement. No statistically significant associations were observed between clinicopathological features and genotypes (P>0.05). The allele frequencies of MLH1 rs63749795 did not differ significantly between patients and controls. However, the rs63749795 polymorphism was associated with reduced OSCC susceptibility under the dominant genetic model (OR = 0.53, 95% CI = 0.29-0.96, P = 0.03 for CT+TT vs. CC genotype). Conclusions : The MLH1 rs63749795 polymorphism may be associated with reduced susceptibility to OSCC under the dominant genetic model; however, although further studies involving larger populations are needed.