Single nucleotide polymorphisms in glutathione S-transferase P1 and M1 genes and overall survival of patients with ovarian serous cystadenocarcinoma treated with chemotherapy.

ABSTRACT

The effects of platinum-based drugs are controlled by genes that are involved in DNA detoxification, including glutathione S-transferase (GST)P1 and GSTM1, which have been associated with increased benefits in the chemotherapeutic treatment of patients with ovarian cancer. The present study assessed the effect of single nucleotide polymorphisms in GST genes on the overall survival (OS) of patients with ovarian serous cystadenocarcinoma that were treated with chemotherapy. A total of 95 patients received treatment with a carboplatin-based or alternative chemotherapy. Polymorphisms in the patients were genotyped using the following methods: Pyrosequencing, to identify GSTP1 Ile105Val; a relative quantification method, to identify the copy number variation in GSTM1; and polymerase chain reaction followed by gel electrophoresis, to identify the null vs. non-null genotypes of GSTM1. The association between genotypes and OS of patients was assessed using Kaplan-Meier survival curves and Cox proportional hazards regression analysis. The OS of patients treated with paclitaxel + carboplatin-based chemotherapy was significantly increased, compared with patients treated with alternative forms of chemotherapy (P=0.035). The OS of patients did not differ significantly between different GSTP1 genotypes (log-rank test, P=0.17). Cox proportional hazards regression analysis revealed that, since the start of the treatment, there was not a significant association between the GSTP1 isoleucine allele and the OS for heterozygous carriers of the isoleucine allele [hazards ratio (HR), 1.78; 95% confidence interval (CI), 0.77-4.12; P=0.18] and no homozygous carriers of the valine allele had been detected (HR, 0.00). There was no significant difference between GSTM1 genotypes, according to Kaplan-Meier survival analysis (log-rank test, P=0.83). Patients that possessed ≤1 copy of GSTM1 exhibited no decrease in OS (HR, 0.96; 95% CI, 0.37-2.51; P=0.94), compared with patients that possessed two copies of GSTM1 (HR, 0.71; 95% CI, 0.22-2.28; P=0.56). Overall, the present results suggest that there are no associations between polymorphisms in the GSTP1 and GSTM1 genes and the OS of patients with ovarian cancer following administration of adjuvant chemotherapy.