Background: Breast cancer is both the prevailing malignancy and the most common cause of cancer death among women. Many factors may play a role in the susceptibility to the breast cancer and Oxygen Free Radicals may be one of these. There are various known antioxidant systems against oxidative stress, including ParaoxonaseI. The aim of this study was to investigate the association between rs854560 polymorphism in the PON1 gene in patients with breast cancer.

Materials and Methods: We performed genotyping analysis using polymerase chain reactionrestriction fragment length polymorphism (PCR-RFLP) assay in a case–control study of 83 confirmed breast cancer patients and 100 cancer-free controls in Markazi Province.

Results: In our study of the PON1 gene L55M polymorphism, the LL genotype was found in 2 (2.40%) patients, whereas the LM genotype was found in 69 (83.13%) patients. The MM genotype was present in 12 (14.45%) patients. In the control group, LL, LM and MM genotypes were found in 4 (4%), 81 (81%), and 15 (15%) subjects, respectively. There was no statistically significant difference between patient and control groups in terms of the PON1 gene L55M polymorphism (p= 0.825). Allele distributions were different but this difference did not reach statistical significance (p= 0.920).

Conclusion: We found no association between M55L polymorphism and breast cancer.