DNA stool test for colorectal cancer:: Hypermethylation of the secreted frizzled-related protein-1 gene

PURPOSE: To investigate a potential mode of noninvasive screening for colorectal cancer, we evaluated the hypermethylation of the secreted frizzled-related protein-1 gene promoter in human stool DNA. METHODS:In stool samples from 36 patients with colorectal neoplasia (7 adenoma, 29 colorectal cancer) and 17 healthy control subjects, isolated DNA was treated with sodium bisulfite and analyzed by methylation-specific polymerase chain reaction with primers specific for methylated or unmethylated promoter sequences of the secreted frizzled-related protein-1 gene. RESULTS:Hypermethylation of the secreted frizzled-related protein-1 promoter was present in the stool DNA of patients with adenoma and colorectal cancer. A sensitivity of 89 percent and specificity of 86 percent were achieved in the detection of colorectal neoplasia. The difference in hypermethylation status of the secreted frizzled-related protein-1 promoter between the patients with colorectal neoplasia and the control group was statistically highly significant (P<0.001). Adenoma and early tumor Stage I (International Union Against Cancer) displayed both unmethylated and methylated secreted frizzled-related protein-1 promoter sequences, whereas advanced tumor stages showed only methylated secreted frizzled-related protein-1 (P=0.05). CONCLUSIONS:The results indicate that this DNA stool test of hypermethylation of the secreted frizzled-related protein-1 promoter is a sensitive and specific method. It has the potential of a clinically useful test for the early detection of colorectal cancer.