ESR1 promoter hypermethylation does not predict atypia in RPFNA nor persistent atypia after 12 months tamoxifen chemoprevention

Abstract

Purpose: Currently, we lack biomarkers to predict whether high-risk women with mammary atypia will respond to tamoxifen chemoprevention.

Experimental design: Thirty-four women with cytologic mammary atypia from the Duke University High-Risk clinic were offered tamoxifen chemoprevention. We tested whether ESR1 promoter hypermethylation and/or estrogen receptor (ER) protein expression by immunohistochemistry predicted persistent atypia in 18 women who were treated with tamoxifen for 12 months and in 16 untreated controls.

Results: We observed a statistically significant decrease in the Masood score of women on tamoxifen chemoprevention for 12 months compared with control women. This was a significant interaction effect of time (0, 6, and 12 months) and treatment group (tamoxifen versus control) P = 0.0007. However, neither ESR1 promoter hypermethylation nor low ER expression predicted persistent atypia in Random Periareolar Fine Needle Aspiration after 12 months tamoxifen prevention.

Conclusions: Results from this single institution pilot study provide evidence that, unlike for invasive breast cancer, ESR1 promoter hypermethylation and/or low ER expression is not a reliable marker of tamoxifen-resistant atypia.

Figure 1

ESR1 promoter hypermethylation. A. Methylation-specific PCR control assays detected 0.1% methylated sequence (1 ng of positive control supplemented with unmethylated cell line for a total of 1 μg genomic DNA). Titration experiments were as described in Materials and Methods; ESR1 M, hypermethylation of the ESR1 promoter. B. Hypermethylation of the ESR1 promoter in RPFNA obtained from representative high-risk women with atypical RPFNA. M and U, the use of methylation-specific PCR primers to identify methylated and unmethylated ESR1 promoter, respectively. (+), a hypermethylated positive control in the M gels and the T47D breast cancer cell line unmethylated positive control in the U gels. (−), negative PCR control.

Figure 2

Median Masood score from tamoxifen-treated women with persistent atypia or loss of atypia. The 17 women that completed 12 mo of tamoxifen treatment were divided into 2 groups: persistent aytpia (▲, Masood score of ≥14) or loss of atypia at 12 mo (■, Masood score of <14). The median Masood value at 0, 6, and 12 mo for these two groups was plotted over time. There was a statistically significant difference in the median Masood score at 12 mo (P = 0.001). Errors bars, 95% confidence interval.