The elusive dream is that a simple blood test could detect a small tumor growing in your body, giving doctors time to cure you before it’s too late.
Using full-genome sequencing to analyze DNA shed into the blood by dying tumor cells, the widely watched company [GRAIL] saw evidence of cancer in 65% of a group of patients already known to have early disease.
The results are similar to those published recently by other research teams. Together, they show that there is “tremendous promise” for finding cancer early using these assays, known as liquid biopsies, says cancer researcher Daniel Haber.
GRAIL is cataloging cancer-related mutations in cell-free DNA in the blood of people with 20 types of cancer and others who are apparently cancer-free.
GRAIL performed three different kinds of assays that analyzed DNA across the entire genome. One looked for mutations in about 500 known cancer genes, a second detected abnormal numbers of copies of genes, and the third analyzed patterns of methylation, which are chemical tags on DNA that turn genes off or on.
…[I]t may never be possible to detect more than about 65% to 70% of early cancers because many small tumors don’t shed enough DNA into the blood.
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