The presented study tests the hypothesis that variations (T-129C, C1236T, G2677T/A, and C3435T) in the ABCB1 gene, which forms a biological barrier against toxins/xenobiotics, may influence the risk of lung cancer and may be a prognostic marker in patients with non-small cell lung cancer (NSCLC). The gene discussed is ABCB1; the disease is lung cancer.