Background: Breast cancer is the first leading cause of cancer-related death in women. Pesticides which are excessively used in northern Iran are one of the most important risk factors for breast cancer incidence. The cytochrome P450 1A1 (cyp1A1) is a key enzyme in xenobiotics metabolism and SNPs of its coding gene has been verified to be important in cancer susceptibility. The aim of this study was to evaluate the association of cyp1A1 M1 polymorphism with the risk of breast cancer in Mazandaran province.

Materials and Methods: Ninety six breast cancer patients with known clinopathological characters and 110 healthy women as control were genotyped for cyp1A1 M1 polymorphisms by PCR-RFLP technique using Msp1 restriction enzymes. Logistic regression model was applied for statistical analysis.

Results: The frequency of TT and TC genotypes of M1 polymorphism was calculated 86, 14% for cases and 79 and 21% for control group, respectively. Surprisingly, the mutant CC genotype was not found in any subjects. Statistical analysis showed no significant correlation between allelic variants and breast cancer risk (p value= 0.42, OR=0.66, CI= 0.24-1.81). No significant correlation was also found between genotypic frequency and clinopathological characters.

Conclusion: Only TT and TC genotypes were found in the studied subjects. The M1 allelic variants were significantly associated neither with breast cancer risk nor with clinopathological characteristics.