Testing may begin within the year. The findings are reported in the October 11 issue of the Proceedings of the National Academy of Sciences. The test identifies replication errors in DNA that occur frequently in cancer. The test uses these errors, called clonal markers, as a fingerprint for cancer.
Clonal markers are a definitive indicator of cancer.
Sidransky and his team used a technique known as polymerase chain reaction, or PCR, to amplify and detect several of these markers in primary human cancers. They then used the same method to look for matching clonal markers in samples, including urine, sputum, and surgically removed tissue, from five patients with symptoms of cancer. They detected cancer cells in all of the samples examined. In healthy people, these errors usually are repaired quickly in the DNA replication process and go undetected. In cancer, however, they occur in cells along with genetic mutations that cause uncontrolled cell growth.