ESR1 and cancer: ER+/PR+ comprised 83,375 (57%) of all 146,176 cancers with known stage, with 33,103 ER−/PR− (23%), 11,540 (8%) ER+/PR−, 2,657 (2%) ER−/PR+, 13,012 (9%) unknown for both ER and PR, and 2,489 (2%) all other categories combined (comprised mainly of ER+/PR unknown, and ER and/or PR borderline).