Due to the different mechanisms of cell-free DNA production, the single-stranded DNA to double-stranded DNA ratio in blood maybe different between healthy individuals and gastric cancer (GC) patients. We aimed to explore the potential application of this ratio in GC diagnosis. The plasma cell-free DNA extracts from 118 healthy individuals and 106 GC patients were prepared. The levels of single-stranded DNA or double-stranded DNA in plasma, and the single-stranded DNA to double-stranded DNA ratio on the diagnostic efficiency for GC were assessed with ROC curve. The relationships between this ratio and the clinical characteristics of GC patients were analyzed. The ratios in 63 GC patients before and after surgery were compared. In healthy individuals, the single-stranded DNA to double-stranded DNA ratio was not affected by factors including age, gender and BMI, and subjected to normal distribution (P = 0.1090). GC patients had a lower value of this ratio than healthy individuals (P < 0.0001). Considering this ratio as a GC diagnostic indicator, the area under ROC curve (AUC) was 0.923[95% confidence interval (CI):0.880–0.955]. This ratio in unresectable GC was obviously lower than that in resectable GC (P = 0.0045). There was a rank correlation between this ratio and GC TNM staging (rho = −0.266, P = 0.0058), but it had no correlation with tumor size (r = 0.14, P = 0.145). Additionally, this ratio was not affected by hemolysis and repeated freeze-thaw of blood samples, and was significantly elevated after surgery(P < 0.0001). The single-stranded DNA to double-stranded DNA ratio in plasma is a stable non-invasive indicator for GC diagnosis.

由于无细胞DNA产生的机制不同，健康个体与胃癌（GC）患者之间血液中单链DNA与双链DNA的比率可能有所不同。我们旨在探讨该比率在气相色谱诊断中的潜在应用。制备了118名健康个体和106名GC患者的无浆细胞DNA提取物。用ROC曲线评估血浆中单链DNA或双链DNA的水平，以及单链DNA与双链DNA之比对GC的诊断效率。分析了该比率与GC患者临床特征之间的关系。比较63例胃癌患者手术前后的比例。在健康个体中，单链DNA与双链DNA的比例不受年龄，P  = 0.1090）。GC患者的该比率值低于健康个体（P  <0.0001）。将该比率作为GC诊断指标，ROC曲线下面积（AUC）为0.923 [95％置信区间（CI）：0.880-0.955]。不可切除GC的比率明显低于可切除GC的比率（P  = 0.0045）。该比率与GC TNM分期之间存在等级相关性（rho = -0.266，P  = 0.0058），但与肿瘤大小无关（r  = 0.14，P  = 0.145）。此外，该比例不受溶血和反复冻融的影响，并且在手术后显着升高（P <0.0001）。血浆中单链DNA与双链DNA的比率是GC诊断的稳定非侵入性指标。