HR and breast cancer: Regarding the BC patients in this analysis, the most common tumor subtype was HR+/HER2− (7996/11,553; 69.2%), followed by HR−/HER2− (2528/11,553; 21.9%), HR+/HER2+ (709/11,553; 6.1%), and HR−/HER2+ (320/11,553; 2.8%).