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Blood Screening Beats Biopsy in Finding Cancer Mutations

A simple blood sample turned up cancer-causing mutations more frequently than a tumor biopsy in a study that suggests the approach could help deliver a clearer picture of the disease and better tailor patients’ treatments.

In a study of Bayer’s drug Stivarga, researchers analyzed tissue and blood samples from patients with gastrointestinal stromal tumors, or GIST, to find cancer-driving mutations. They found that blood samples were more likely to reveal them than biopsies, in results presented yesterday at the American Association for Cancer Research meeting in Washington.

As cancer treatments increasingly home in on known genetic causes of the disease, researchers need better tools to determine just what mutations each patient has, said George Demetri, director of the Ludwig Center at Dana-Farber Cancer Institute and Harvard Medical School, who led the trial. Samples taken from tumors may not reveal all the underlying mutations at once, he said in an interview.

“A biopsy is by definition a subset of the tumor cells,” Tyler Jacks, director of the Koch Institute for Integrative Cancer Research at the Massachusetts Institute of Technology, said in a telephone interview. He wasn’t associated with the research. “What’s cool about this idea is the use of the blood sample as a surrogate to what’s happening in the tumor.”

The screen, called BEAMing technology, is sensitive enough to detect even rare mutations circulating in the blood stream in the form of free DNA, genetic material shed from tumors. Demetri said he expects the testing technology could become a standard part of caring for cancer patients within five to 10 years.

The analysis was done as part of Leverkusen, Germany-based Bayer’s trial of Stivarga, a cancer therapy approved in February for GIST and last year for colorectal cancer. Researchers took DNA from tumor tissue and analyzed it for mutations in two genes known to drive cancer-causing proteins targeted by Bayer’s drug and medicines from Pfizer and Novartis, Sutent and Gleevec.