Genetic Polymorphism of GSTP1: Prediction of Clinical Outcome to Oxaliplatin/5-FU-based Chemotherapy in Advanced Gastric Cancer

The aim of this study was to evaluate the predictive value of the polymorphism Glutathione S-transferase P1 (GSTP1) Ile¹⁰⁵Val on oxaliplatin/5-FU-based chemotherapy in advanced gastric cancer. Patients with advanced gastric cancer accepted oxaliplatin/5-FU-based chemotherapy as first-line chemotherapy were investigated. GSTP1 Ile¹⁰⁵Val polymorphism was detected by TaqMan-MGB probe allelic discrimination method. Response to treatment was assessed by disease controlled rate. Time to progression, overall survival and toxicities were recorded. Final patient outcomes were as follows: the allele frequencies of GSTP1 were ¹⁰⁵Ile/¹⁰⁵Ile 52%, ¹⁰⁵Ile/¹⁰⁵Val 41% and ¹⁰⁵Val/¹⁰⁵Val 7%. For patients with ¹⁰⁵Ile/¹⁰⁵Ile and those with at least one ¹⁰⁵Val allele, disease control rate was 39% and 71% (P=0.026), respectively; median time to progression was 4.0 and 7.0 months (P=0.002); median overall survival time was 7.0 and 9.5 months (P=0.002). Neurological toxicity was more frequently occurred in patients with two ¹⁰⁵Ile alleles (P=0.005). In conclusion, patients with at least one ¹⁰⁵Val allele have better prognosis and response to oxaliplatin/5-FU-based regimen as first-line treatment for patients with advanced gastric cancer.