ESR1 and breast carcinoma: In 2011, the ATAC trial (Arimidex, Tamoxifen, Alone or in Combination) examined the prognostic value of combining those four immunohistochemistry markers among 1125 ER positive breast cancer patients in comparison with another multiparameter test—Oncotype DX, or Genomic Health Recurrence Score—covered in the next section (79).