Sequencing was also performed on DNA from white blood cells. “That’s very important. The white blood cells are rich with mutations that can pollute the DNA and make you think that there is cancer present in the cell-free DNA,” Dr. Oxnard explained. “You screen out this interference from the white blood cells and other biologic noise, and you are left with the final features: mutations, copy number variations, and methylation signatures that then go into the final assays being studied.”
Results showed that when assay specificity was 98%, sensitivity for early-stage (stage I-IIIA) lung cancer ranged from 38% to 51%, and sensitivity for late-stage (stage IIIB-IV) lung cancer ranged from 87% to 91%.
Among five presumed cancer-free individuals having positive results on all three assays, two subsequently received a cancer diagnosis (one with stage III ovarian cancer, one with stage II endometrial cancer).
An additional 19 cancer types across all stages were tested in the CCGA substudy. Early results for breast, gastrointestinal, gynecologic, blood, and other cancers were also reported at the meeting (abstracts 536, 12021, and 12003).