The first cohort evaluated for CDR1-AS expression consisted of RNA isolated from primary tumours from LNN breast cancer patients, including oestrogen receptor (ER, ESR1)-positive and ER-negative patients, who did not receive systemic adjuvant therapy (n = 345) (see the REMARK diagram in Supplementary Fig. 1) (prognostic cohort). This evidence concerns the gene ESR1 and breast cancer.