DNA Test Shows Promise for Breast Cancer Care
Blood sample helps doctors assess treatment response, researchers say
For 10 of those 19 women, tumor DNA was on the rise an average of five months before CT scans showed their cancer was progressing.
"The take-home message is that circulating tumor DNA is a better monitoring biomarker than the existing Food and Drug Administration-approved ones," said senior researcher Dr. Carlos Caldas.
It all suggests that the test could help in monitoring women's treatment response, said Yuan, who was not involved in the study.
But while she said the findings are "exciting," she also stressed that a lot more work needs to be done.
"This is nowhere near being ready for clinical practice," Yuan said. "But this is one direction we're heading in."
There are other tests being developed for monitoring women with breast cancer, Yuan noted. One is a test that looks for abnormalities in DNA "copy number." A recent preliminary study found that this approach might help predict some women's risk of a breast cancer recurrence.
And researchers are still studying existing tests to see how they can best be used. The blood test that detects tumor cells -- sold in the United States as the CellSearch system -- can be used to help monitor women in treatment for metastatic breast cancer. In general, a higher number of tumor cells means a quicker progression.
But for now, professional guidelines do not recommend that doctors routinely use the test because its ultimate usefulness is still unclear, said Dr. Anthony Lucci, a surgical oncologist at the University of Texas M.D. Anderson Cancer Center in Houston.
The new findings suggest that the tumor DNA test is more sensitive than the existing tumor cell test, said Lucci, who was not involved in the research.
He said that in the future, it might be helpful in monitoring women with metastatic cancer or in helping to spot a breast cancer recurrence earlier.
Earlier detection of recurrences is the big hope, said Dr. Jorge Reis-Filho, an attending pathologist at Memorial Sloan-Kettering Cancer Center in New York City. "If changes in DNA happen before changes are seen in imaging," he said, "that could help us be more proactive in treatment."