The Women's Health Initiative study reported a 24% relative increase in breast cancer risk with HRT, but the absolute risk increase was only 0.1 percentage points.

“this large clinical trial involving thousands of older women compared a multitude of Health outcomes in women taking HRT versus those who did not take it the study reported a 24 relative increase in the risk of breast cancer among a subset of women taking HRT and headlines all over the world condemned HRT as a dangerous cancer-causing therapy all of a sudden on the basis of this one study HRT became virtually taboo this reported 24 risk increase sounded scary indeed but nobody seemed to care that the absolute risk increase of breast cancer for women in the study remained minuscule roughly five out of every one thousand women in the HRT group developed breast cancer versus four out of every one thousand in the control group who received no hormones the absolute risk increase was just 0.1 percentage point”