MDR1 gene C3435T polymorphism is associated with clinical outcomes in gastric cancer patients treated with postoperative adjuvant chemotherapy

Objective: To evaluate the impact of the multi-drug resistance 1(MDR1) C3435T polymorphism on clinical outcomes in gastric cancer patients treated with postoperative adjuvant chemotherapy. Methods: From January 2005 to December 2008, 102 patients with surgically resected gastric cancers were enrolled into this study in the Affiliated Jiangsu Cancer Hospital of Nanjing Medical University. The polymorphism was tested using real time polymerase chain reaction (RT-PCR) cycling probes and the relationship with clinical outcomes after postoperative adjuvant chemotherapy was analyzed by SPSS 17.0. Results: The CT/TT genotype of C3435T was significantly associated with a shorter progression-free survival (PFS) and overall survival (OS) compared with the CC genotype PFS: adjusted hazard ratio(HR)= 2.01, 95% confidence intervals(CI): 1.17-3.45, P = 0.012; OS: adjusted HR = 2.37, 95% CI: 1.31-4.28, P=0.004]. TNM stage was also associated with PFS (adjusted HR = 2.33, 95% CI: 1.34-4.05, P = 0.003) and OS (adjusted HR = 2.62, 95% CI: 1.44-4.76, P = 0.002) in gastric cancer patients treated with postoperative adjuvant chemotherapy. Conclusion: Our results suggest that the MDR1 gene C3435T polymorphism is associated with clinical outcomes in gastric cancer patients treated with postoperative adjuvant chemotherapy. This now needs to be confirmed by a randomized prospectively controlled study.