Using a recently developed molecular test, investigators at The Johns Hopkins University School of Medicine have detected genetic mutations specific to cancer in blood samples of six patients with head and neck cancer. Their findings are reported in the September issue of Nature Medicine.
"Although quite preliminary, these findings are interesting, because the presence of DNA alterations in the blood appears to be associated with large, advanced tumors and with cancer that has spread," says lead author David Sidransky, M.D., associate professor of otolaryngology/head and neck surgery, and oncology. Sidransky cautions that the test does not appear useful as a screening test for cancer. "But it might be helpful in patient management for identifying patients with a very poor prognosis who may benefit from aggressive therapy," he says.
The test works by identifying replication errors, or chromosomal deletions, in the DNA of cancer cells. In this study, the investigators examined DNA from patients' serum (a component of blood plasma) and compared this DNA pattern to normal DNA from circulating white blood cells. They found genetic alterations in the serum of 6 of 21 head and neck cancer patients that were identical to alterations from the tumor itself.
Examining disease outcomes, the researchers found that 4 out of the 6 patients with positive test results subsequently died of their cancer compared to only 3 of 15 with negative test results. Additionally, the three patients who developed distant metastases (disseminated cancer) were in the positive test group, further indicating that poor outcome may be associated with the presence of serum DNA alterations. These results must be confirmed in much larger clinical trials, Sidransky says.
The technique used in this study was developed by Sidransky's team and first used to detect cancer cells in urine. The test uses a series of DNA markers to seek out genetic
mutations specific to each patient's cancer
Contact: Karin Twilde
Johns Hopkins Medical Institutions