This news came out today - it's very interesting and ties the drop in use of Premarin and Prempro to a decrease in the incidence of breast cancer.

http://www.pantagraph.com/articles/2006/12/14/news/doc4...4735345014815669.txt

A New England Journal of Medicine study links the reduced rate of breast cancer with the reduced use of hormone replacement therapy.

Read the original NEJM study here:
http://content.nejm.org/cgi/content/full/356/16/1670

Or read a Consumer Affairs article about it here:
http://www.consumeraffairs.com/news04/2007/04/hrt_breast_cancer.html