A team from the USA investigated the possibility of developing molecular tests for the detection of colorectal cancer in stool samples.
51 colorectal cancer patients were enrolled in the study. Stool DNA was isolated from paired stools and primary tumor samples from each subject.
Three genetic targets - TP53, BAT26, and K-RAS - were used to detect tumor-associated mutations in the stool, prior to or without regard to the molecular analyses of the paired tumors.
TP53 gene mutations were detected in the tumor DNA of 30 patients. All of these individuals had the identical TP53 mutation in their stools.
|They detected 92% patients whose tumors had at least one genetic mutation.
|Journal of the National Cancer Institute|
Tumors from 3 patients contained a non-inherited deletion at the BAT26 locus. These were the same as those found in the stool specimens.
19 of 50 tumors tested had a K-RAS mutation. The researchers detected identical mutations in the paired stool DNA samples from 8 patients.
In no case was a mutation found in stool that was not also present in the primary tumor.
When taken together, the three genetic markers detected 36 (71%) of 51 patients with colorectal cancer. They also detected 36 (92%) of 39 patients whose tumors had at least one genetic mutation.
Seung Myung Dong, of the Johns Hopkins Medical School, Baltimore, Maryland, said on behalf of the group, "We were able to detect the majority of colorectal cancers by analyzing stool DNA for just three genetic markers."
"Additional work is needed to determine the specificity of these genetic tests, for detecting colorectal neoplasia in asymptomatic patients. More precise estimates of the prevalence of the mutations and sensitivity of the assay are needed," it was concluded.