Objective To study the genetic regulation mechanism of colorectal LST,polypoid adenomas and clolrectal cancer by detecting the expression of p53,c-myc and Ki-67 in these three lesions.Methods The expressions of p53,c-myc,Ki-67 were determined via two-step of immunohistochemistry method in LST,polypoid adenomas,invasive colorectal cancer and their significant difference were compared.Statistical analyses were used to analyze the correlation among Ki-67 expression and p53,c-myc expression in these three group lesions.Results Immunohistochemical staining was performed in 38 LST,62polypoid adenomas and 36 colorectal cancer.For p53 and c-myc,the positive rates in LST,polypoid adenomas and colorectal cancer were significantly different from each other.For Ki-67,the positive rates in LST and polypoid adenomas were significantly lower than that in colorectal cancer,but there was no statistical significant difference between LST and polypoid adenomas.The expression of Ki-67 did not correlate with p53and c-myc both in LST and polypoid adenomas.But in colorectal cancer,the expression of Ki-67 was strongly related to p53 and c-myc.Conclusion The expressions of p53,c-myc and Ki-67 were different in LST,polypoid adenomas and colorectal cancer,indicating that their genetic regulation mechanism might be different,and the genetic avenue for LST may be different from polypoid adenomas.

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 mu-tation rate about the APC,p53 and K-ras genes using polymerase chain reaction single strand conformation poly-morphism 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.How-ever 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.Con-clusion Fecal DNA testing is expected to become an effective noninvasive colon tumor early diagnosis and screening method.