Objective To evaluate the possibility of detection mutations of 〖JP2〗multiple genes in stool for secondary screening for colorectal cancer. Methods Tumor specimens and stool samples from 40 patients with colorectal cancer and 40 normal persons were examined for mutations of p53, K-ras and APC gene by polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) and silver nitrate staining. Results ①The mutation rate of p53, K-ras and APC gene in the tissues and stools of colorectal cancer respectively were 57.50%, 50.00%, 60.00% and 42.86%, 40.00%, 51.43%, and no mutations were found in normal mucosa and stool. ②The mutation ratioes between multiple gene and single gene had significant difference (P＜0.05). ③The sensitivities had no significant difference between faecal occult blood test (FOBT) and multiple gene mutations detection in the diagnosis of colorectal cancer, but the specificity of the latter was higher than FOBT (P＜0.05). Conclusion Detection of multiple gene mutations in stool is a vauble method in the secondary screening for colorectal cancer.
Objective To evaluate the diagnostic accuracy of the aberrant methylation of genes in stool for colorectal tumor. Methods Databases including The Cochrane Library, PubMed, EMbase, CBM, Web of Science, CNKI and WanFang Data were searched to collect the diagnostic trials on the aberrant methylation of genes in stool for colorectal tumor published from January 1990 to February 2012. QUADAS items were used to evaluate the quality of the included studies, and the meta-analysis was conducted using Meta-Disc 1.4 software. Results A total of 32 studies involving 3 951 patients were included. The results of meta-analysis showed that, for detecting the colorectal tumor, the weighted sensitivity, specificity, diagnostic odds ratio (DOR), area under the summary receiver operating characteristic (SROC) curve and Q were 92% (95%CI 91% to 93%), 63% (95%CI 61% to 65%), 20.79 (95%CI 15.13 to 28.57), 0.861 9 (SE=0.020 4), and 0.792 6 (SE=0.019 8), respectively. For detecting the colorectal cancer, the weighted sensitivity, specificity and area under the curve (AUC) were 91% (95%CI 89% to 92%), 75% (95%CI 73% to 77%), and 0.900 7, respectively. For detecting the colorectal adenoma, the weighted sensitivity, specificity and AUC were 79% (95%CI 76% to 83%), 75% (95%CI 73% to 77%), and 0.845 7, respectively. Conclusion With high sensitivity (92%) and moderate specificity (63%), aberrant methylation of genes in stool can be used as an optional noninvasive method for the diagnosis of colorectal tumor.