Effect of Contemporary Exposure to Mixed Organic Solvents and Occupational Noise on Hearing Thresholds of Workers

: Background: Resistance to drugs with different structure and function is a great obstacle to the successful treatment of breast cancer. A well-known mechanism responsible for drug resistance is over-expression of ABC-transporter genes such as MDR1. MDR1 gene polymorphisms may result in drug resistance. In this study we investigated the possible correlation between MDR1 gene C3435T polymorphism and clinicopathologic findings and response to treatment in Iranian breast cancer patients. Materials and Methods: In this descriptive study we investigated C3435T polymorphism of MDR1 gene in 54 breast cancer patients admitted to Imam Khomeini Hospital of Tehran and 40 individuals without history of breast cancer by PCR-RFLP technique during 2006-2008. Association of this polymorphism with response to treatment and clinicopathologic characteristics were also investigated. Data were analyzed using Chi-Square test and SPSS software. P values<0.05 were considered to be statistically significant. Results: In patient group frequencies of genotypes were 18% for CC, 56%for CT and %26 for TT whereas in control group frequencies of genotypes were %23 for CC, %50 for CT and %27 for TT. There was no significant difference in frequency of C3435T polymorphism between breast cancer patients and healthy controls. Frequency of C3435T polymorphism between responders and non-responders was not significant. Conclusions: It seems that there is no correlation between C3435T polymorphism of MDR1 gene and response to treatment, clinical findings and pathologic characteristics of breast cancer. So the role of C3435T polymorphism in response to treatment is still controversial.