Hormone Hazards

Women who use unopposed estrogen generally have had their ovaries removed or have other health issues. How does that affect the difference in risk?
Women who have had a hysterectomy, particularly an oophorectomy [in which the ovaries and sometimes the fallopian tubes are removed], will have a lower risk of breast cancer regardless of whether or not they take hormones. That is because breast cancer risk is driven by hormones produced by the ovaries. The sooner that ovarian production of hormones stops—and it would typically occur earlier in a woman who had her ovaries removed—the lower the lifetime risk of breast cancer.

Why are epidemiological studies like yours an important tool for following this and understanding risk?
The advantage of this type of study is really that we can collect very detailed information from women and we can also get tumor tissue blocks. The WHI was a big study, but it had certain limitations because it was so big. It was more expensive. They didn't collect any tumor tissue blocks in that study, so this is the first study to confirm what the actual histology was by a centralized histology review.

© 2008