CLINICAL SIGNIFICANCE OF SALIVARY MIR-21, -155, AND -375 IN PATIENTS WITH SQUAMOUS CELL CARCINOMA OF ORAL CAVITY.

Background: The current prognostic markers in oral squamous cell carcinoma (OSCC) have limited accuracy sometimes leading to inappropriate treatment decisions. Identifying new markers would help clinicians tailor treatment plans based on the individual patient risk factors leading to improved survival rates and quality of life.

Aim: To estimate the value of the miRNA expression indicators in saliva as prognostic and predictive markers of the effectiveness of neoadjuvant chemotherapy (NACT).

Materials and methods: The work is based on the results of the examination and treatment of 61 patients with stage II-IV OSCC. The miR-21, miR-155, and miR-375 expression levels in the saliva samples were analyzed by the real-time reverse transcription polymerase chain reaction.

Results: The salivary miR-21 and -155 expression levels in healthy volunteers were 2.49 and 2.84 times lower than in OSCС patients (p < 0.05). The positive association of miR-21 and miR-155 expression levels and the negative correlation of miR-375 expression level with T index by TNM (r = 0.68, r = 0.75, and r = -0.67, respectively) (p < 0.05) and the presence of lymph node metastasis (r = 0.78, r = 0.71, and r = ‒0.59, respectively) (p < 0.05) were found. Patients with good response to NACT had lower miR-21 and -155, and higher miR-375 levels in saliva compared to those with resistant tumors.

Conclusions: Our study suggests that salivary miR-21, miR-155, and miR-375 may be potential biomarkers for the prognosis of cancer course and the response to NACT in OSCC patients.