The WHI study found an increase in breast cancer incidence of about one case per thousand women per year but no difference in breast cancer mortality.

“so at the time that the study was halted really the big headline of the study was estrogen causes breast cancer I use this as a great teaching example when I talk about the difference between relative risk and absolute risk the relative risk difference in the group that was Cee plus MPA relative to Placebo or versus placebo was 24 25 correct yes I think it was a little higher on the surface that sounds incredibly startling right so women who are getting CE plus MPA have a 25 percent higher risk of breast cancer during this 5.2 year period”