['Serum lactate dehydrogenase (LDH) has been reported as a prognostic biomarker in malignant diseases. However, little is known on the dynamics of serum LDH levels during systemic treatment. We focused on the association of changes in serum LDH with outcome of patients with advanced-stage non-small cell lung cancer (NSCLC) treated with erlotinib.', 'Clinical data of 309 patients were analyzed. Serum samples were collected within one week before initiation and after one month of treatment.', 'The change in serum LDH during the first month of erlotinib treatment was independently associated with disease control rate (p=0.006), progression-free survival (PFS) (p=0.010) and overall survival (OS) (p<0.001).'] Does change in Serum Lactate Dehydrogenase be Associated with Outcome of Patients with Advanced-stage NSCLC Treated with Erlotinib?