摘要目的:对比血浆胞裂蛋白9(septin 9，SEPT9)和多配体蛋白聚糖2前体(syndecan-2，SDC2)甲基化联合检测与4种血清肿瘤标志物对结直肠癌诊断效果的差异。方法:本研究选择2019年3—12月在徐州医科大学附属医院就诊的128例患者为研究对象进行病例对照研究。所有研究对象均行胃肠镜检查，根据病理结果分3组，结直肠癌组74例，结直肠腺瘤组7例，以胃肠镜检查未见异常或有炎性息肉或增生性息肉者作为对照组(47例)。128例研究对象均采用罗氏Lightcycler 480Ⅱ实时荧光定量聚合酶链式反应仪检测血浆SEPT9基因和SDC2基因甲基化的水平，采用罗氏Cobas 8000电化学发光仪检测血清甲胎蛋白、癌胚抗原、糖类抗原125和糖类抗原199的浓度，采用χ 2检验比较各标志物在3组中的阳性检出率，采用Medcalc绘制受试者工作特征曲线(receiver operating characteristic curve，ROC)，对各指标诊断结直肠癌的价值进行分析。 结果:SEPT9基因和SDC2基因甲基化在结直肠癌组的单独阳性检出率分别为81.1%(60/74)和67.6%(50/74)，当两个基因甲基化联合检测后提升至85.1%(63/74)。甲胎蛋白、癌胚抗原、糖类抗原125和糖类抗原199在结直肠癌组中阳性检出率分别为1.4%(1/74)、33.8%(25/74)、6.8%(5/74)、13.5%(10/74)，4种肿瘤标志物联合检测时仅提升至43.2%(32/74)，3组阳性检出率比较，除了甲胎蛋白和糖类抗原125外(χ 2值分别为3.847、2.430， P均>0.05)，其余各指标组间比较差异均有统计学意义( P均<0.05)。SEPT9甲基化、SDC2甲基化、甲胎蛋白、癌胚抗原、糖类抗原125和糖类抗原199用于预测诊断结直肠癌的曲线下面积(area under the curve，AUC)(95% CI)分别为0.854(0.781，0.910)、0.795(0.715，0.861)、0.575(0.485，0.662)、0.685(0.597，0.764)、0.603(0.513，0.689)和0.631(0.541，0.715)，两种DNA甲基化标志物联合检测的AUC(95% CI)为0.872(0.801，0.924)，4种血清肿瘤标志物联合检测的AUC(95% CI)为0.712(0.625，0.789)。两种DNA甲基化标志物联合检测的AUC优于甲胎蛋白、癌胚抗原、糖类抗原125、糖类抗原199的AUC，差异均有统计学意义(甲胎蛋白： Z＝4.990， P<0.001；癌胚抗原： Z＝3.743， P<0.001;糖类抗原125： Z＝4.951， P<0.001;糖类抗原199： Z＝3.983， P<0.001)；两种基因甲基化联合检测的AUC优于4种血清标志物联合检测对结直肠癌的诊断，差异有统计学意义( Z＝3.334， P<0.001)。 结论:血浆中SEPT9基因和SDC2基因甲基化联合检测比4种血清肿瘤标志物联合检测更适合结直肠癌非侵入性诊断。

abstractsObjective:To compare the difference between the combined diagnostic effect of plasma Septin9(SEPT9) and polyligand Syndecan-2(SDC2) methylation with four serum tumor markers in the diagnosis of colorectal cancer.Methods:In this study, 128 patients who were treated in the affiliated Hospital of Xuzhou Medical University from March to December in 2019 were selected for a case-control study.All the subjects were examined by gastroenteroscopy.According to the pathological results, they were divided into three groups: colorectal cancer group( n=74) and colorectal adenoma group( n=7). The patients with no abnormal or inflammatory polyps or proliferative polyps examined by gastroenteroscopy were taken as the control group( n=47). The methylation levels of SEPT9 gene and SDC2 gene were detected by Roche Lightcycler 480 II real-time fluorescence quantitative polymerase chain reaction, and the concentrations of alpha-fetoprotein, carcinoembryonic antigen, carbohydrate antigen 125 and carbohydrate antigen 199 were detected by Roche Cobas 8000 electrochemiluminescence instrument.Chi-square test was used to compare the positive rate of each marker in the three groups.Medcalc was used to draw the receiver operating characteristic curve (ROC) curve of the subjects′ working characteristic curve, and the value of each index in the diagnosis of colorectal cancer was analyzed. Results:The positive rates of SEPT9 gene and SDC2 gene methylation were 81.1%(60/74) and 67.6%(50/74) respectively in colorectal cancer group, and increased to 85.1%(63/74) after combined detection.The positive detection rates of alpha-fetoprotein, carcinoembryonic antigen, carbohydrate antigen 125 and carbohydrate antigen 199 in colorectal cancer group were 1.4%(1/74), 33.8%(25/74), 6.8%(5/74) and 13.5%(10/74), respectively.When the four tumor markers were detected together, the positive detection rates were only increased to 43.2%(32/74), except for AFP and carbohydrate antigen 125(χ 2=3.847, 2.430, all P>0.05). The differences were statistically significant (χ 2=48.230, 30.487, 43.285, 3.847, 8.788, 6.988, 8.722, all P<0.05). The area under the curve (AUC) of SEPT9 methylation, SDC2 methylation, alpha fetoprotein, carcinoembryonic antigen, carbohydrate antigen 125 and carbohydrate antigen 199 were 0.854 (0.781, 0.910), 0.795 (0.715, 0.861), 0.575 (0.485, 0.662), 0.685 (0.597, 0.764), 0.603 (0.513, 0.689) and 0.631 (0.541, 0.715), respectively.The AUC of combined detection of two DNA methylation markers was better than that of alpha fetoprotein, carcinoembryonic antigen, carbohydrate antigen 125 and carbohydrate antigen 199, and the differences were statistically significant (alpha fetoprotein: Z=4.990, P<0.001; carcinoembryonic antigen: Z=3.743, P<0.001; carbohydrate antigen 125: Z=4.951, P<0.001; carbohydrate antigen 199: Z=3.983, P<0.001). The combined detection of two kinds of gene methylation was better than the combined detection of four kinds of serum markers in the diagnosis of colorectal cancer, and the difference was statistically significant ( Z=3.334, P<0.001). Conclusion:The combined detection of SEPT9 gene and SDC2 gene methylation in plasma is more suitable for non-invasive diagnosis of colorectal cancer than the combined detection of 4 serum tumor markers.