Abstract
BACKGROUND: Tumor markers such as serum carcinoembryonic antigen (CEA) and cytokeratin fragment 19 (CYFRA 21-1) are utilized for assessing the effectiveness of chemotherapy in non-small cell lung cancer (NSCLC) patients. Yet, it remains uncertain whether these markers can reliably forecast responses to combined chemoimmunotherapy. Our study aimed to examine the significance and effectiveness of these markers in predicting responses among NSCLC patients undergoing combined chemoimmunotherapy. METHODS: This two-part observational study involved patients with NSCLC who were treated with combined chemoimmunotherapy in Japanese hospitals. An initial retrospective study of these patients, with serum CEA and CYFRA 21-1 as prognostic factors for combined chemoimmunotherapy outcomes, served as a discovery cohort. Patients in a subsequent prospective study served as a validation cohort, where we assessed the prognostic accuracy of CEA and CYFRA 21-1 cut-off points determined by the discovery cohort. RESULTS: In total, 121 patients treated with combined chemoimmunotherapy were included, with 44 and 77 patients in the discovery and validation cohorts, respectively. Serum CYFRA 21-1 levels >3.0 ng/mL were significantly associated with progression-free survival (PFS) in both the discovery and validation cohorts (P=0.01, P=0.04, respectively). PFS did not differ significantly by CEA levels (P=0.21). CONCLUSIONS: After combined chemoimmunotherapy treatment, serum CYFRA 21-1 stands out as a potentially valuable biomarker for predicting the prognosis of NSCLC.