In July 2002, WHI researchers reported a 26% increase in breast cancer for postmenopausal women taking estrogen plus progestin. In June 2003, researchers reported that the combination hormone therapy may also stimulate breast cancer growth and delay breast cancer diagnosis. In this current study, researchers conclude that short-term use of estrogen plus progestin is associated with a decreased incidence of colorectal cancers. However, these cancers are diagnosed at more advanced stage perhaps related to symptom misinterpretation or other reasons requiring further study.
According to Dr. Chlebowski: "The effects of estrogen plus progestin suggest that use of these hormones can delay diagnosis of breast and colorectal cancer, two of the three most common malignancies of postmenopausal women. The risks and benefits of combined hormone use should be evaluated prior to beginning this treatment."
Citation: The New England Journal of Medicine, March 4, 2004
New England Journal of Medicine