Molecular profiling is critical for personalized treatment in patients with non-small cell lung cancer (NSCLC), researchers noted in Translational Lung Cancer Research. However, obtaining adequate tumor tissue for genotyping can be challenging, especially in advanced-stage disease.

To address this knowledge gap, researchers evaluated droplet digital polymerase chain reaction (ddPCR) analysis of bronchial washings and serum for detecting driver oncogene mutations in patients with NSCLC. The prospective, multicenter, observational study included 73 patients with NSCLC who underwent bronchoscopy with bronchial washing collection and blood sampling.

The researchers performed ddPCR on bronchial washing and serum samples to detect epidermal growth factor receptor (EGFR; L858R, exon 19 deletions, G719X), KRAS (G12/13), and BRAF (V600E) mutations. The primary outcomes measured were sensitivity, specificity, and concordance rate of driver oncogene mutation detection compared with standard tissue genotyping methods. The study team also assessed turnaround time for results. The median age of patients was 74 years, with the majority (63%) being men. Regarding smoking status, 78.1% were current smokers. The primary histologic subtype was adenocarcinoma, accounting for 72.6% of cases.

Efficacy of Bronchial Washings in NSCLC

The study demonstrated the high accuracy and rapid turnaround time of ddPCR analysis on bronchial washings for detecting NSCLC driver mutations, indicating that the strategy represents a viable alternative in the molecular profiling of NSCLC, according to the researchers.

ddPCR analysis of bronchial washing samples identified EGFR mutations in 31.5% of cases, which was identical to the mutation rate seen in tumor tissue. For the most common EGFR mutations (L858R and exon 19 deletion), bronchial washing genotyping showed 100% sensitivity and 98% specificity versus tissue genotyping.

The researchers noted a significantly shorter turnaround time for bronchial washing samples assessed by ddPCR compared with tissue genotyping (4.4 ±1.8 vs 20.4 ±7.7 days; P<0.001). Serum ddPCR showed limited use compared with tissue genotyping (7.8% vs 33.3% for EGFR mutations), with detection associated with the presence of bone metastases (83.3% vs 29.4%, respectively; P=0.05), with the researchers noting that serum ddPCR may complement tissue genotyping in specific clinical scenarios.

“The implementation of [bronchial washing] ddPCR in clinical settings offers several potential benefits, including reduced invasiveness compared to tissue biopsy, faster [turnaround time], and the ability to perform repeated testing for monitoring purposes,” the study authors wrote.