Hormone therapy and the rise and perhaps fall of US breast cancer incidence rates: critical reflections

Results of the Women's Health Initiative (WHI) study-which to many unexpectedly showed that hormone therapy (HT) did not decrease and may in fact have elevated risk of cardiovascular disease, while also finding expected links between HT and breast cancer-have spurred critical reflection chiefly regarding the cardiovascular results. Suggesting similar scrutiny of cancer epidemiology is warranted are new studies linking the post-WHI drop in HT use to a substantial decline in breast cancer incidence and the implications of these findings for prior explanations of the rising rates of US breast cancer incidence during the 1980s.