The estrogen-alone arm of the Women's Health Initiative (WHI) showcased the finding but they are contradictory to the previous which reported three years ago that postmenopausal women given both estrogen and progestin showed a definite spike in breast cancer risk.
Marcia Stefanick, a researcher from the Stanford University School of Medicine, who is also the lead author shows hope that these latest findings will help clarify the issue for women unnerved by the seemingly contradictory results of hormone replacement research.
In her words, "The good news is we confirmed the preliminary data that there was no increase in breast cancer in the study population overall, which was really different from the estrogen-plus-progestin trial. The issue for women who have had a hysterectomy with respect to the concern about breast cancer is very different from estrogen combined with progestin. If you have a uterus, you have a totally different issue to consider and that is going on hormones does increase your risk of breast cancer.
This Women's Health Initiative has for the past 15 years studied causes and prevention of conditions and diseases affecting women 50 and older, among them hormone replacement therapy for menopause symptoms.
In this trial the effects of estrogen versus placebo in almost 11,000 women, aged 50 to 79, over seven years were compared. It was designed to conclude after eight years, but was halted 12 months early after increased rates of stroke and blood clots in the legs were found among those taking estrogen.
"When we talk about the menopause-aged women, most 50-year-old women are not at very high risk for stroke or hip fracture, so where they have the biggest concern is for breast cancer," she concluded.