Abstract: Objective To investigate the expression of long non-coding RNA (lncRNA) brain-derived neurotrophic factor-antisense (BDNF-AS) and semaphorin 3B-antisense 1 (SEMA3B-AS1) in patients with gastric cancer and the application value of combined ultrasound in the diagnosis of gastric cancer.Methods From January 2021 to February 2023,118 gastric cancer patients admitted to our hospital were retrospectively selected as the gastric cancer group,another 113 cases with benign gastric lesions in our hospital were as the benign lesion group.Real-time fluorescence quantitative PCR (qRT-PCR) was applied to detect the expression levels of serum BDNF-AS and SEMA3B-AS1,and patients were divided into BDNF-AS high expression group (n=55) and BDNF-AS low expression group (n=63),SEMA3B-AS1 high expression group (n=57),and SEMA3B-AS1 low expression group (n=61) based on the average value;Kappa test was applied to analyze the consistency between ultrasound diagnosis and clinical pathological diagnosis;receiver operating characteristic curve (ROC) was applied to analyze the diagnostic value of serum BDNF-AS and SEMA3B-AS1 combined with ultrasound for gastric cancer.Results Compared with the benign lesion group,the serum levels of BDNF-AS and SEMA3B-AS1 in the gastric cancer group were obviously lower (t=10.205,t=9.590,P＜0.05);the expression levels of BDNF-AS and SEMA3B-AS1 were obviously lower in gastric cancer patients with tumor diameter ≥ 3 cm,deeper infiltration depth,lower differentiation,and lymph node metastasis (P＜0.05);Kappa test results showed a high consistency between ultrasound diagnosis and clinical pathological diagnosis (Kappa value=0.723,P＜0.05);ROC results showed that the AUC of serum levels of BDNF-AS,SEMA3B-AS1,and ultrasound in diagnosis of gastric cancer was 0.848,0.835,and 0.861,respectively,the AUC (0.949) diagnosed by the combination of the three was obviously higher than that diagnosed by serum BDNF-AS alone (Z=4.713,P=0.000),serum SEMA3B-AS1 level alone (Z=4.112,P=0.001 5),and ultrasound diagnosis (Z=3.350,P=0.000 8),the sensitivity and specificity of the combined diagnosis were superior to those diagnosed by the three alone.Conclusion The combination of serum BDNF-AS and SEMA3B-AS1 ultrasound has high practical value in the diagnosis of gastric cancer.

Key words: gastric cancer, ultrasound, long non-coding RNA, brain-derived neurotrophic factor-antisense, semaphorin 3B-antisense 1, diagnosis