Breast cancer outcome and estrogen plus progestin use in postmenopausal women.

1507 Background: During a mean (SD) 5.6 years (1.3) of intervention, use of estrogen plus progestin in the Women's Health Initiative (WHI) randomized clinical trial increased breast cancer incidence (Chlebowski et al JAMA 2003;289;3243) but breast cancer mortality was not reported. Therefore, we determined combined hormone therapy effects on breast cancer incidence and mortality in the WHI trial over the entire follow-up period (mean [SD] 11.0...