Polymorphism in the androgen receptor and mammographic density in women taking and not taking estrogen and progestin therapy.

There is some evidence that women with a higher number of CAG repeat lengths on the androgen receptor (AR) gene have increased breast cancer risk. We evaluated the association between AR-CAG repeat length and mammographic density, a strong breast cancer risk factor, in 404 African-American and Caucasian breast cancer patients. In postmenopausal estrogen progestin therapy users, carriers of the less active AR-CAG had statistically significantly higher mean percentage of density (41.4%) than carriers of the more active AR-CAG (25.7%; P = 0.04). Our results raise the question of whether the number of AR-CAG repeats predicts breast cancer risk in estrogen progestin therapy users.

The HRAS1 variable number of tandem repeats and risk of breast cancer.

Rare alleles at the HRAS1 variable number of tandem repeats (VNTRs) locus have been implicated in breast cancer risk. We assessed the association of rare HRAS1 alleles and breast cancer in a case-control study nested within the Nurses' Health Study cohort. Using PCR-based methods, 717 incident breast cancer cases and 798 controls were genotyped for the HRAS1 VNTRs. The prevalence of the rare alleles in breast cancer cases was not different compared with controls (10.7 versus 12.0%, respectively; P = 0.45, two-sided Cochran-Mantel-Haenzel chi(2) test). There was no evidence that women heterozygous (multivariate odds ratio, 0.97; 95% confidence interval, 0.73-1.27) or homozygous (multivariate odds ratio, 0.83; 95% confidence interval, 0.32-2.14) for rare alleles were at an increased risk of breast cancer or that a positive gene-dose effect existed. The results did not vary by menopausal status. Although as a group the rare alleles were not associated with breast cancer, one class of rare alleles between the common alleles of a3 and a4 was associated with a significantly increased risk. These results suggest that there is no overall association between rare alleles of the HRAS1 VNTR and breast cancer.