探讨粪便K ras基因检测在老年大肠癌临床诊断中的价值。收集连续就诊的 2 3例老年大肠癌患者、2 0例结肠腺瘤性息肉患者及 2 0名健康老年查体者的粪便 ,并从中提取DNA ,应用等位基因特异性杂交技术检测粪便K ras基因第 12位密码子第 1、2位碱基突变情况。结果K ras基因突变率在大肠癌患者为 5 6 5 2 % (13/ 2 3) ,明显高于正常查体者的 5 % (1/ 2 0 ) (P <0 0 1) ,与结肠腺瘤性息肉组的 30 % (6 / 2 0 )比较 ,差异无显著性意义 (P >0 0 5 )。 92 31% (12 / 13)的大肠癌K ras基因突变位点发生在第 12位密码子第 2位碱基。研究表明 ,结肠癌患者组织及粪便中K ras基因突变的检出具有良好的一致性 ,提示粪便中检测K ras基因突变是一种无创性的老年大肠癌的诊断方法 To investigate the value of stool K ras gene detection in clinical diagnosis of colorectal cancer. Stool samples from 23 consecutive patients with colorectal cancer, 20 patients with adenomatous polyposis coli and 20 healthy elderly patients were collected and DNA was extracted. Allele-specific hybridization was used to detect stool K ras Gene 12th codon 1st and 2nd base mutation. Results The mutation rate of K ras gene was 56.2% (13/2 3) in colorectal cancer patients, which was significantly higher than that in normal subjects (5% (1/20)) (P <0.01) There was no significant difference in 30% (6/20) of polypoid tumor (P> 0.05). 92 31% (12/13) of the K ras gene mutations in colorectal cancer occurred at the 12th codon base. Studies have shown that the detection of K ras gene mutations in the tissues and faeces of patients with colon cancer has a good consistency, suggesting that the detection of K ras gene mutation in the stool is a noninvasive method for the diagnosis of elderly colorectal cancer