Prognostic Impact of the ABCC11/MRP8 Polymorphism in Adjuvant Oral Chemotherapy with S-1 for Non-Small Cell Lung Cancer

Background: Postoperative 1-year administration of S-1, an oral derivative of 5-fluorouracil (5-FU), was shown to be feasible in lung cancer. The 5-year survival rates of postoperative patients treated with S-1 adjuvant chemotherapy and the prognostic impact of clinicopathological factors were examined. Methods: The data of 50 patients with curatively resected pathological stage IB to IIIA non-small cell lung cancer, who were treated with S-1 postoperatively, were analyzed. The prognostic impacts of 22 clinicopathological factors including expressions of the 5-FU pathway enzymes were evaluated. A single-nucleotide polymorphism (SNP), i.e. 538G>A (rs17822931), of ABCC11/MRP8, which encodes a 5-FU excretion enzyme that is known as an earwax type determinant, was also evaluated. Results: The 5-year overall and relapse-free survival rates were 72.5 and 67.5%, respectively. A performance status ≥1, lymphatic vessel invasion, blood vessel invasion, and the A/A type of SNP538, which is responsible for the dry earwax type, were significantly associated with shorter relapse-free survivals. In 34 patients who showed a relative performance of 70% or more for chemotherapy, multivariate survival analysis indicated significant hazard ratios only for the A/A type of SNP538 (p = 0.007). Conclusions: S-1 has sufficient power as adjuvant chemotherapy. However, its effect might be small in the dry earwax type patient group in an adjuvant setting.