Thymidylate synthase expression is closely associated with outcome in patients with pulmonary adenocarcinoma

The aim of this study is to elucidate the prognostic significance of thymidylate synthase (TS), orotate phosphoribosyltransferase (OPRT) and dihydropyrimidine dehydrogenase (DPD) in completely resected non-small cell lung cancer (NSCLC). One hundred and sixty patients with NSCLC were included in this study. Tumor sections were stained by immunohistochemistry for TS, OPRT, DPD, glucose transporter 1 (Glut1), hypoxia inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF), microvessel density (MVD) determinated by CD34, epidermal growth factor receptor (EGFR), phosph-Akt, phosph-mammalian target of rapamycin (mTOR) and p53. TS, OPRT and DPD were positively expressed in 46, 71 and 54%, respectively. The expression of TS and OPRT was significantly higher in patients with non-adenocarcinoma (non-AC) (n = 53) than adenocarcinoma (AC) (n = 107), and DPD expression was higher in adenocarcinoma as compared with non-adenocarcinoma. A positive TS expression was an independent prognostic factor for predicting a poor outcome in patients with AC, but not in those with non-AC. In AC patients, TS expression was significantly associated with advanced stage, lymph node metastases, vascular invasion, Glut1, HIF-1α, angiogenesis, EGFR signaling pathway and p53. In patients with non-AC, TS expression was not closely correlated with outcome and these biomarkers. A positive TS expression was a powerful prognostic factor to predict a poor outcome in completely resected AC patients.