Polymorphisms in the estrogen receptor alpha gene and mammographic density

Area of Science:

• Genetics
• Oncology
• Epidemiology

Background:

• The estrogen receptor alpha gene (ESR1) is crucial in breast cancer development.
• Previous studies suggest a link between ESR1 polymorphisms (PvuII, XbaI) and breast cancer risk, but findings are inconsistent.
• Mammographic density is a strong risk factor for breast cancer.

Purpose of the Study:

• To investigate the association between ESR1 PvuII and XbaI polymorphisms and mammographic density.
• To explore whether ESR1 genotypes and haplotypes influence breast density, a known breast cancer risk factor.

Main Methods:

• A cohort of 620 women aged 49-68 from the European Prospective Investigation into Cancer and Nutrition (EPIC) cohort was studied.
• Genotyping for ESR1 PvuII and XbaI polymorphisms was performed using TaqMan PCR assay.
• Mammographic density was quantified using a computer-assisted method and compared across genotypes and haplotypes.

Main Results:

• Higher mammographic density was observed in women with PvuII p allele (Pp, pp) and XbaI x allele (Xx, xx) compared to PP and XX genotypes, respectively.
• Specific ESR1 haplotypes (px and PX) showed an allele-dose effect on both percentage and absolute breast density.
• P-trends for XbaI and haplotype associations with density were statistically significant (<0.01).

Conclusions:

• ESR1 polymorphisms, specifically PvuII and XbaI, are associated with variations in mammographic density.
• These findings suggest that ESR1 genetic variations may contribute to breast cancer risk by modulating breast density.