Interventional pulmonology use of cell-free DNA assay for metastatic non–small cell lung cancer: the UC Davis experience

Background: Interventional pulmonologists (IPs) are often the first specialist to see patients with suspected metastatic non–small cell lung cancer (mNSCLC). Consequently, they are potentially ideally positioned to expedite the identification of actionable molecular mutations by ordering blood-based cell-free DNA (cfDNA), prior to or upon tissue diagnosis of mNSCLC. Methods: Retrospective review of cfDNA ordered by IP as part of a routine clinical practice. Patients were categorized into two groups based on when cfDNA was ordered by IP: (1) IP suspected mNSCLC prior to histologic confirmation or (2) IP diagnosed mNSCLC based on histologic confirmation of NSCLC. Results: Twenty patients were identified. Twelve of 13 in group 1 were confirmed to have mNSCLC by oncology and 1 had stage IIIA. Seven of 7 in group 2 were confirmed to have mNSCLC by oncology. Fifteen of 20 also had next-generation tissue molecular testing. Thirteen of 20 (65%) had targetable alterations. Seven of 13 (54%) were identified on cfDNA and tissue, 5/13 (38%) on cfDNA only, and 1/13 (8%) on tissue alone. Tissue results were available a medium of 24 days after, and cfDNA results a medium of 4 days prior to, the patients’ first oncology visit. Conclusions: IP appears to be able identify patients who have mNSCLC and for whom testing for molecular mutations is appropriate even prior to tissue confirmation of NSCLC. A strategy whereby IP employ blood-based cfDNA testing in suspected and tissue confirmed mNSCLC could potentially provide medical oncologists with more timely information on actionable mutations than tissue-based testing first, potentially expediting patient treatment.