FIGO news - Scientists discover three genes linked to breast cancer | International Federation of Gynecology and Obstetrics

Note: the PLOS Genetics paper is technical,  references Tamoxifen

"The study, which is published in the journal PloS Genetics, found the genes - C6ORF96, C6ORF97 and C6ORF211 - located next to the oestrogen receptor gene. According to the research, the three genes were linked to the oestrogen receptor but worked separately from it."

study excerpt:
"These findings suggest that the genes could contribute to the phenotype associated with oestrogen-receptor positivity. In addition, they may be involved in the mechanism by which genetic variation in this region of the genome contributes to breast cancer susceptibility."