Stephen J.LurieMD, PhD, Senior Editor
To the Editor: Both the WHI trial1 and earlier observational studies2 have found an unacceptably high excess risk of breast cancer with increasing duration of use of combined estrogen plus progesterone. Findings for venous thrombosis, stroke, colon cancer, and fractures were also similar to those predicted by observational studies. Observational studies, however, suggested that HRT may prevent CHD, while the WHI found evidence of increased risk. While some have suggested that the discordance is due to uncontrolled confounding in the observational studies, these studies actually address different questions.
Speizer FE. Risks of Postmenopausal Hormone Replacement. JAMA. 2002;288(22):2819. doi:10.1001/jama.288.22.2819-JLT1211-1-2