A comparative study on various methods of fecal exfoliated cell testing for screening of colorectal cancer / 中华消化杂志

ABSTRACT

Objective To evaluate the effect of various methods of fecal exfoliated cell testing for screening of colorectal cancer.Methods The stool samples from 814 patients who underwent colonoscopy were collected for fecal exfoliated cell testing using diarrhea feces,twice naturally evacuated feces,magnetic separation or naturally evacuated combined with diarrhea feces.The fecal exfoliated cells were isolated and examined cytologically.The DNA quantitative analysis and gene detection were carried out.Fecal occult blood test was simultaneously performed in twice naturally evacuated feces and naturally evacuated combined with diarrhea feces.Results The sensitivity and specificity of exfoliated cells testing for colorectal Cancer was 66.27%(112 of 169 cases of colorectal cancer)and 99.56%(225 of 226 normal subjects),respectively.There was no correlation of positive rate with differentiations of colorectal cells or Duke's stages(P＞0.05).The nuclear DNA quantitative analysis showed that the sensitivity for detecting cancer was 76.09%for twice naturally evacuated feces and 68.29%for naturally evacuated combined with diarrhea feces,which was superior than diarrhea feces(26.31%)and magnetic separation (43.24%).The positive rate of genes detected in carcinoma tissues concordant with fecal exfoliated cells testing were 83.33%(25/30)for p53,9/10 for APC and 9/10 for K-ras.The sensitivity of cytology was higher than gene detection.The sensitivity of cancer detection was higher in combining exfoliated cells test with fecal occult blood test(93.10%)than exfoliated cells test(73.56%)or fecal occult blood test (80.46%)alone(P＜0.05).Conclusions Fecal exfoliated cells test is an effective method for screening of colorectal cancer.It is the best option for detecting cancer by twice tests of fecal exfoliated cells with liquid-based thin-layer cytological test,and combined with fecal occult blood test.