Intratumoral gene expression of 5-fluorouracil pharmacokinetics-related enzymes in stage I and II non-small cell lung cancer patients treated with uracil-tegafur after surgery: A prospective multi-institutional study in Japan

• We assessed gene expression levels of 5-FU related enzymes in stage I/II NSCLC.
• Tumors from 236 patients with UFT administration after surgery were examined.
• Thymidylate synthase gene expression was an independent predictive factor for DFS.

ObjectivesThis investigation was conducted to assess the use of the intratumoral mRNA expression levels of nucleic acid-metabolizing enzymes as biomarkers of adjuvant chemotherapy for non-small cell lung cancer (NSCLC) using uracil-tegafur in a multi-institutional prospective study.Materials and methods236 patients with a completely resected NSCLC (adenocarcinoma and squamous cell carcinoma) of pathological stage IA (maximum tumor diameter of 2 cm or greater), IB, and II tumors were given a dose of 250 mg of uracil-tegafur per square meter of body surface area per day orally for two years after surgery. Intratumoral mRNA levels of thymidylate synthase (TS), dihydropyrimidine dehydrogenase (DPD), orotate phosphoribosyltransferase (OPRT), and thymidine phosphorylase (TP) genes relative to an internal standard, β-actin, were determined using laser-capture microdissection and fluorescence-based real time PCR detection systems.Results and conclusionAmong 5-FU target enzymes, TS was the only one that showed a significant difference in the level of gene expression between the high and low gene expression groups, for both disease-free survival (DFS) and overall survival (OS), when patients were divided according to median values; 5-year DFS rates in high/low TS gene expression were 60.4% and 72.6%, respectively (p = 0.050), 5-year OS rates were 78.1% and 88.6%, respectively (p = 0.011). Cox's proportional hazard model indicated that the pathological stage and TS gene expression level were independent values for predicting DFS.The TS gene expression level was shown to be an independent predictive factor for DFS in stage I and II NSCLC patients who were treated with uracil-tegafur following surgery.