LAUSR

Introduction The role of serum tumor markers in the modern management of advanced NSCLC remains poorly described. Methods A single‐center retrospective analysis of available carcinoembryonic antigen, CA125, CA19.9, and CA27.29 levels at baseline and during treatment of stage IV lung adenocarcinoma by oncogenic driver was conducted. Results A total of 142 patients were analyzed (60 with anaplastic lymphoma kinase gene [ALK] rearrangement, 50 with EGFR mutation, four with ROS1 rearrangement, and 29 with KRAS mutation). Of these, 82% had at least one marker (95% if all four markers were measured), with CA27.29 being the most commonly increased and CA19.9 the rarest. Only CA27.29 differed significantly by oncogene (it was less common in KRAS) (p = 0.016). The median times to nadir during tyrosine kinase inhibitor (TKI) therapy in EGFR and ALK cases were 16.4 and 20 weeks, respectively. Of the 41 patients with EGFR mutation or ALK or ROS1 rearrangement, 24 (59%) demonstrated an initial increase within the first 4 weeks of TKI therapy, 58% of whom then had their levels fall below baseline. An increase in marker level of 10% or more from nadir occurred in 53% of systemic and 22% of central nervous system–only progression. Conclusions Serum tumor markers are frequently increased in lung adenocarcinoma regardless of driver oncogene. Changes within the first 4 weeks of therapy may be misleading. Progression is associated with marker increases, especially in sites other than the central nervous system.