ESR1 and breast cancer: DNA methylation status of selected tumor suppressor genes (P14, P16, MGMT, RARB, RASSF1, DAPK1, GSTP1, ESR1-1, ESR1-4, PRKCB, MT1E, MT1F, MT1G, APC, ADAMTS12, RUNX3, NAALAD2, and FILIP1L) was analyzed in 116 BC and 29 control samples.