Abstract: Objective To investigate the feasibility and clinical significance of fecal DNA tests for colon tumor diagnosis and screening,we inspected the mutations of APC,p53 and K-ras genes in the tissue and feces of patients with colorectal tumor.Methods We collected 46 patients with colorectal cancer(CRC),60 patients with colorectal adenomas(CRA)and 30 cases of normal person in Huizhou First People Hospital in Guangdong Province from Nov.2011 to Aug.2012.Then all the tumor tissues and feces of these people were detected the mutation rate about the APC,p53 and K-ras genes using polymerase chain reaction single strand conformation polymorphism analysis method(PCR-SSCP).Results The mutation rates of APC,p53,K-ras genes of feces in CRC group,CRA group and normal group were 58.7%(27/46),65.2%(30/46)and 60.9%(28/46),20.0%(12/60),25.0%(15/60)and 23.3%(14/60),3.33%(1/30),0%(0/30)and 0%(0/30),respectively.However the mutation rate in tissues were 63.0%(29/46),69.6%(32/46)and 63.0%(29/46),25.0%(15/60),26.7%(16/60)and 26.7%(16/60),0%(0/30),0%(0/30)and 0%(0/30).Corresponding mutations could be found in feces and tumor tissues.Consistency checking for mutations rate in feces and tumor tissues of CRC group and CRA group showed that the Kappa value were 0.818(P＜0.001),0.901(P＜0.001),0.862(P＜0.001)and 0.857(P＜0.001),0.870(P＜0.001),0.822(P＜0.001).It means an excellent consistency.Conclusion Fecal DNA testing is expected to become an effective noninvasive colon tumor early diagnosis and screening method.

Key words: Fecal DNA, Tissular DNA, Colorectal Tumor, Opportunity Screening