粪、血APC及K-ras基因突变联合检测在大肠癌筛查中的作用

Value of fecal and blood adenomatous polyposis coli gene and K-ras gene mutation detection in colorectal neoplasm screening

目的通过联合检测粪、血浆中APC和K-ras两种基因的突变,探讨其在大肠癌筛查中的作用。方法收集本院2003年10月～2004年3月行肠镜检查患者的肝素抗凝血5ml,大便3～5g。提取粪便及血浆DNA,采用PCR-SSCP法检测APC和K-ras突变。结果和结论(1)大肠癌和腺瘤患者血浆APC基因突变分别为41.9%和57.7%(P>0.05),高于正常对照组(P<0.05)。粪便APC基因突变分别为51.6%和42.3%(P>0.05),高于正常对照组(P<0.05)。两种检测方法具有高度的吻合度(kappa值为0.811,P<0.001)。(2)血浆K-ras基因突变在大肠癌、腺瘤和正常对照分别为48.4%、3.8%和0%,粪便K-ras基因突变在3组中分别为54.8%、7.7%和11.1%,大肠癌组高于腺瘤组和正常组(P<0.05),腺瘤组和正常组间无差异(P>0.05)。两种方法检测的吻合度一般(kappa值为0.662,P=0.000)。(3)联合检测APC及K-ras基因突变可以提高诊断大肠癌的灵敏度。血、粪联合检测检测APC和K-ras基因突变较粪便检测无明显优势。(4)APC基因突变与是否发生肿瘤区域淋巴结转移有关,K-ras基因突变与病变分化程度有关。

Objectives To explore the value of detection of adenomatous polyposis coli （APC） gene and K-ras gene mutations in fecal and blood samples in colorectal neoplasm screening. Methods From 84 subjects undergoing colonoscopic examination （including 31 with colorectal carcinoma, 26 with colorectal adenoma, and 27 healthy subjects） between October, 2003 and March, 2004, 5 ml of heparinized peripheral blood and 3-5 g fecal specimens were collected. The DNA was extracted from the specimens for detecting the mutation of APC and K-rasgene using polymerase chain reaction-single strand conformation polymorphism and the results were analyzed statistically. Results and Conclusion （1） The incidence of APC gene mutation was 41.9% and 57.7% in the plasma, and 34.8% and 26.8% in the fecal specimens of colorectal carcinoma patients and adenoma patients, respectively, both higher than that in normal subjects （P〈0.05）, suggesting high consistency between fecal and plasma APC gene mutation detection （K=0.811, P〈0.05）. （2） The incidence of plasma K-ras mutation was 48.4% in colorectal carcinoma patients, 3.8% in adenoma patients and 0% in normal control subjects, and in the feces, the incidences were 54.8%, 7.7% and 11.1%, respectively. The mutation rate was higher in carcinoma patients than in adenoma patients and normal subjects （P〈0.05）. Fecal K-ras gene mutation detection was consistent with plasma detection （K=0.662, P=0.000）. （3） APC gene mutation detection showed a low sensitivity and specificity in the diagnosis of colorectal carcinoma, but K-ras mutation detection showed a high specificity. The diagnostic sensitivity increased when combining APC and K-ras gene detection in the plasma or fecal specimens, but there was no evidence to suggest that APC and K-ras mutation detection in the plasma could be better than detection in the feces. （4） For colorectal carcinoma, APC gene mutation is associated with lymphoid node metastasis, but not with the patient＇s gender, age, tumor location, differentiation, distant organ metastasis or CEA level （P〉0.05）, and the mutation of K-ras gene is related to the degree of tumor differentiation.