ESR1 and breast cancer: To further test the hypothesis that regions 17q21.33-q25.1, 8p11.2 and 8q24.3 are likely to be amplified in ER+/HER2- breast cancer samples having high Oncotype Dx recurrence scores because of upregulation of cell-cycle genes, a set of 14 ER+/HER2- breast cancer samples with known Oncotype Dx scores was evaluated for the presence of 17q21.33-q25.1, 8p11.2 or 8q24.3 amplifications using FISH.