Introduction: Breast cancer is the second most common cancer in the world and the most common cancer in Iranian women in terms of rate. The cytochrome P-450c17a (CYP17) gene, located on chromosome 10q24.3, encodes the enzyme cytochrome P-450c17a, which functions as a susceptibility factor in breast cancer.
Material and methods: Three common polymorphisms have been described in the CYP17 gene. The variant creates a recognition site for the MspAI restriction enzyme, the common allele as A1 and the variant alleles A2 (–34T ® C). In total 53 Iranian sporadic breast cancer affected women compared to the control group were studied by PCR-RFLP for CYP17 variant.
Results: Even though the A2/A2 were reported as risk factors for breast cancer our results showed that the A1/A1 were a higher risk factor in our population. A2/A2 had an inhibitory effect in our patients [A1/A1 / A2/A2 odds ratio, 5.57 (95% confidence interval, 1.514-20.506) p = 0.008].
Conclusions: We conclude that not only was A2/A2 in our patients not associated with breast cancer risk but also there is a reverse relation between presence of A1/A1 and increase of breast cancer risk.