The Race to Diagnose Cancer With a Simple Blood Test
Five years ago, a team of researchers pored over the results of a prenatal genetic test given to more than 125,000 healthy pregnant women and made a stunning discovery. The blood test, marketed by gene-sequencing giant Illumina, was designed to detect chromosome anomalies associated with conditions such as Down syndrome by analyzing fragments of fetal DNA circulating in the mother’s blood.
In 3,757 of the tests, the scientists found at least one abnormality. But in 10 of those cases, further analysis revealed that the fetuses were in fact normal.
“In every one of those 10 cases, it turned out there was an undiagnosed cancer” in the mother, says Alex Aravanis, who at the time of the study was the senior director of research and development at Illumina.
To Aravanis and the other scientists, the unexpected result suggested a whole new opportunity: a single blood test for detecting multiple types of cancer before a person has any symptoms. “This was really important background science that [suggested] this might be possible,” says Aravanis, a founder and chief scientific officer at Grail, a Menlo Park, California–based startup launched three years ago by Illumina.