Favorable genetic polymorphisms predictive of clinical outcome of chemoradiotherapy for stage II/III esophageal squamous cell carcinoma in Japanese

Objectives: This study was performed to find the genetic factors predictive of clinical outcome to a 5-fluorouracil (5-FU)/cisplatin (CDDP)-based chemoradiotherapy (CRT) in Japanese patients with locally advanced esophageal squamous cell carcinoma (ESCC). Materials and Methods: Thirty-one patients with stage I-IVa ESCC (I/II/III/IVa = 7/7/14/3) were enrolled in this study. One course of treatment consisted of protracted venous infusions (PVIs) of 5-FU (400 mg/m(2)/24 hours for days 1-5 and 8-12), CDDP (40 mg/m(2) /3 hours on days 1 and 8) and radiation (2 Gy/d on days 1-5, 8-12, and 15-19), and a 2nd course was successively repeated after a 2-week interval. A total of 8 measurements of the plasma concentration of 5-FU were made using high performance liquid chromatography. Genetic polymorphisms examined herein included those in the genes coding thymidylate synthase (TS), glutathione S-transferase PI (GSTPI), multidrug resistant transporter MDR1/P-glycoprotein, and intercellular adhesion molecule-1, and in a circadian rhythm-relating gene, CLOCK. Results: The CR rate depended on stage (P = 0.001), but the analysis was not sufficiently powered to reach a level of statistical significance for the 2-year survival rate (P = 0.061). For stage II/III patients, to have 2 or 3 polymorphisms of 3R/3R of 5'-TSER, a 6 bp of 3'-TSUTR, and GSTPI-Ile105Val resulted in an extensively longer survival (P = 0.020), although no difference was found between 2 groups, with respect to the plasma concentrations of 5-FU and clinicopathologic characteristics. Conclusions: The prognostic index may allow predictions of the clinical outcome of a 5-FU/CDDP-based CRT in stage II/III ESCC patients.