Abstract: PURPOSE: To investigate the prognostic value of plasma level of miR-136-5p in patients with oral squamous cell carcinoma (OSCC). METHODS: From January 2015 to October 2018, 86 OSCC patients and 50 normal controls were selected from Danzhou People's Hospital. The expression of miR-136-5p in plasma of the two groups were detected by real-time fluorescence quantitative PCR. The optimal cut-off value of plasma miR-136-5p expression level was determined by ROC curve, and OSCC patients were divided into high miR-136-5p group(n=36) and low miR-136-5p group (n=50). The clinicopathological features of the two groups were compared. Survival curves were drawn by Kaplan-Meier method. Single factor and multi factor Cox regression models in SPSS 20.0 software package were used to analyze the risk factors of poor prognosis in OSCC patients. RESULTS: The expression level of plasma miR-136-5p in OSCC group(1.27±0.51) was significantly lower than that in the control group (4.38±1.26, P<0.01). Low expression of plasma miR-136-5p was related to the clinical stage, differentiation degree, tumor diameter and cervical neck lymph node metastasis of OSCC (P<0.05). Survival analysis showed that the overall survival rate of low miR-136-5p group(48.0%) was significantly lower than that of high miR-136-5p group (68.4%,P<0.01), and the progression-free survival rate of low miR-136-5p group(28.6%) was significantly lower than that of high miR-136-5p group (57.8%,P<0.01). Multivariate Cox regression model analysis showed that clinical stage [HR(95%CI) =2.462(1.805-4.193)], cervical neck lymph node metastasis [HR (95%CI)= 2.913 (2.142-5.827)and plasma miR-136-5p expression<2.82 [HR (95%CI)=3.856 (3.114-8.205)were independent risk factors for poor prognosis of patients with OSCC(P<0.05). CONCLUSIONS: Low expression of plasma miR-136-5p is related to short survival time of OSCC patients, which is expected to be a biomarker for predicting poor prognosis of OSCC.

Key words: Oral squamous cell carcinoma, miR-136-5p, Prognostic prediction