In a recent study published in the famous journal JAMA Oncology?, Sacher and colleagues have shown the true value of liquid biopsy. Blood of the patients with advanced lung cancer was used to do droplet digital polymerase chain reaction (ddPCR) assay for detecting common EGFR and KRAS mutations.? Over one year, the study involved 180 patients with advanced disease, including 120 who were newly diagnosed and 60 who had acquired resistance to an EGFR kinase inhibitor. Patients underwent initial blood sampling and immediate plasma ddPCR for EGFR exon 19 del, EGFR L858R, and/or KRASG12X.? All patients also underwent biopsy for tissue genotyping. Tumor genotype included 80EGFR exon 19/L858R mutants, and 25 KRAS G12X mutants.
The median test turnaround time (in business days) for liquid biopsy ddPCR was 3 days (range = 1–7 days). This was significantly shorter than the median turnaround time for tissue genotyping, which was 12 days (range = 1–54 days) for patients with newly diagnosed disease and 27 days (range = 1–146 days) for patients with acquired resistance.
Plasma ddPCR had positive predictive values of 100% for EGFR 19 del, 100% for L858R, 100% for KRAS. Hence, the authors concluded: “Plasma ddPCR detected EGFR and KRAS mutations rapidly with the high specificity needed to select therapy and avoid repeat biopsies in patients with advanced lung cancer.
At Asian Cancer Institute, this is the advantage that we pass on to our patients using the concept of precision oncology.