CAT and neoplasm: Pro-GRP, a biomarker for small-cell lung cancer (SCLC), ishighly expressed in tumor tissues and has a diagnostic sensitivityof approximately 84% and specificity of 95%. Elevated plasma levels of Pro-GRP are observed in SCLC patients,making it a reliable marker for early detection and monitoring. Additionally, antioxidant proteins, includingSOD, glutathione peroxidase (GPx), catalase (CAT), and glutathionereductase (GR), play crucial roles in mitigating oxidative stress,which is a hallmark of lung cancer pathophysiology.