CHICAGO – according to the first interim report from a substudy of the large, ongoing Circulating Cell-free Genome Atlas (CCGA).
“Lung cancer screening with low-dose CT is known to improve outcomes. And yet, CT-based lung cancer screening is not widely adopted,” said lead study author Geoffrey R. Oxnard, MD, associate professor of medicine at Dana-Farber Cancer Institute and Harvard Medical School, Boston, in a press briefing at the annual meeting of the American Society of Clinical Oncology, where the study was reported. “Criticisms of low-dose CT include the risk of false positives and overdiagnosis. We proposed to investigate an untapped opportunity for cancer detection, which is using cell-free DNA.”
Susan London/MDedge News
Dr. Geoffrey R. Oxnard
Main substudy results among 164 patients with lung cancer and 923 comparable individuals without known cancer showed that at a specificity of 98%, the three assays evaluated detected up to 51% of early-stage (stage I-IIIA) lung cancers and up to 91% of late-stage (stage IIIB-IV) lung cancers. And among the healthy participants with false-positive results for lung cancer, several were ultimately found to have cancers of other types.
“This first interim analysis of the CCGA study demonstrates that comprehensive sequencing of the plasma cell-free DNA can generate high-quality data across the entire genome, and it permits noninvasive cancer detection. The assays can detect lung cancer across stages, across histologies, across populations,” Dr. Oxnard said.
“Together, these results support the promise of using cell-free, DNA-based assays to develop an early cancer detection test with high specificity. Further assay and clinical development is ongoing: There is a separate prospective trial enrolling, the STRIVE study, and there remain thousands of patients still on this CCGA study to be analyzed for further optimization and focusing of this assay towards an eventual cancer diagnostic.”
The cohort studied was not a screening population, so the assays’ performance cannot be compared with that of low-dose CT at this point, he said. But the hypothesis going forward is that the assays will have comparatively higher specificity, sparing some patients an unnecessary diagnostic work-up.
The population in which the final blood test might be used will depend on its diagnostic performance once the assays are fully refined and clinic ready, which will take some time, according to Dr. Oxnard. However, “2 years ago, this was a pipe dream. Two years ago, it was completely just a brainstorm that had no data to support it, and I didn’t believe that this could be done. Today, we actually have data to show that this is really feasible to find early-stage cancer in the blood. So this is a huge step forward and actually means that this is going to be a reality.”