In 1993, the National Institute for Health (NIH) began recruitment for a study that was meant to definitively answer questions relating to HRT. HRT had, for decades, been viewed as a positive thing for women, a "fountain of youth" of sorts; however, the true effects had never been studied on a large scale.
The study, the Women's Health Initiative (WHI), would have a specific HRT trial involving 16,000 postmenopausal women who would receive either a placebo or a specific HRT program. The study was ended approximately 3 years early as data coming in from the study indicated some alarming trends. The researchers found that the women who were placed on HRT had a 26% increase in the risk of breast cancer, 41% increase in strokes, 100% increase in venous thromboembolic events (blockage of blood vessels) and a 29% increase in heart attacks.
As a result of the aforementioned findings, the researchers decided to immediately end the HRT portion of the study and announced their findings to the public so that medical professionals could act appropriately.
While these numbers may seem alarming, they must be taken in context. For example, the increase in risk for the development of breast cancer equates to approximately 1 additional case per 1,000 women per year. There are still many women who will continue to remain on HRT in spite of the increased risk, feeling that the benefit provided is greater than the risk posed.
Of course, be sure to speak with your health care professional before making any medical decisions. HRT is not appropriate for everyone. Decisions should only be made on a case-by-case basis as each woman's body is different.