Association of the Alu insertion polymorphism in the progesterone receptor gene with breast cancer in a Mexican population

Introduction: The progesterone receptor (PR) gene plays an important role in reproduction-related events. Data on polymorphisms in the PR gene have revealed associations with cancer, particularly for the Alu insertion polymorphism, which has been suggested to affect progesterone receptor function and contribute to tumor promotion in the mammary gland. Material and methods: We examined the role of the Alu insertion polymorphism in the PR gene by comparing the genotypes of 209 healthy Mexican women with those of 481 Mexican women with breast cancer (BC). Results: The genotype frequencies observed in the controls and BC patients were 0% and 4% for T2/T2 (Alu insertion), 16% and 21% for T1/T2, and 84% and 75% for T1/T1 (Alu deletion), respectively. The obtained odds ratio (OR) was 1.7, with a 95% confidence interval (95% CI) of 1.1-2.6, p = 0.009, for the T1/T2-T2/T2 genotypes. The association was also evident when the distributions of the T1/T2-T2/T2 genotypes in patients in the following categories were compared: obesity grade II (OR = 1.81, 95% CI: 1.03-3.18, p = 0.039) and the chemotherapy response (OR = 1.91, 95% CI: 1.27-3.067, p = 0.002). Conclusions: The T1/T2-T2/T2 genotypes of the Alu insertion polymorphism in the PR gene are associated with BC susceptibility in the analyzed Mexican population.