We studied 39 consecutive NSCLC patients and measured the expression of six molecular markers (MDR-1, LRP, RRM-1, EGFR, ERCC-1, BRCA-1) in their primary tumors and metastatic lymph nodes and four well-known serum markers for cancer (NSE, CEA, CA-125, CYFRA 21-1). The gene discussed is ABCB1; the disease is cancer.