In recent years, concerns have been growing regarding the use of estrogen-progestin therapy to alleviate menopausal symptoms in women. The turning point came in 2002 with a pivotal government-sponsored trial called the Women’s Health Initiative (WHI). This trial had to abruptly halt a branch involving a combination of estrogen and progestin due to a shocking revelation: women using these hormone therapies faced an increased risk of strokes, heart attacks, and breast cancer.
This unsettling discovery prompted countless women to discontinue hormone therapy altogether. However, a recent and somewhat controversial reevaluation of the data has unveiled some intriguing findings, especially for a specific group of women who rely solely on estrogen without progestin to manage their menopausal symptoms. Surprisingly, it appears that these women may actually have a reduced risk of developing breast cancer.
This reevaluation, presented at the recent San Antonio Breast Cancer Convention, immediately stirred debate among some scientists who claimed it was simply a rehash of older data. Nevertheless, Dr. J. Ragaz, the advocate of this report and a researcher at the University of British Columbia, asserted that the potential protective effect of estrogen against breast cancer had been largely overlooked and deserved more attention.
Dr. Ragaz emphasized that this information had been neglected, leaving the oncology community uninformed. He pointed out that these findings were highly significant as they added to the body of evidence supporting estrogen’s potential role in protecting against breast cancer.
The WHI trial, involving 17,000 women using combination therapy, was halted in 2002. However, a second part of the trial included 10,000 women who had undergone a hysterectomy and were either taking only estrogen or a placebo (progestin is typically used to counteract the adverse effects of estrogen on the uterine region). The estrogen-only trial was halted prematurely two years later, before the full impact of estrogen could be thoroughly assessed. Nevertheless, subsequent analyses published in JAMA in 2004 and later at the San Antonio meeting presented statistically significant data suggesting that estrogen intake significantly reduced the risk of breast cancer in specific subsets of women.
For example, among the 8,500 women with no family history of breast cancer, estrogen use reduced the risk of the disease by 32% compared to those who took a placebo. Among the 7,600 women with no history of benign breast conditions, such as lumps or cysts, those who took estrogen had a 43% lower risk of developing breast cancer.
It’s crucial to understand that this does not mean women should rush to start taking estrogen for breast cancer prevention. However, the accumulating evidence may provide reassurance to women who have had a hysterectomy and are using estrogen to alleviate menopausal symptoms. Approximately one-third of postmenopausal women have undergone a hysterectomy.
Dr. Ragaz and other experts argue that these findings open up a new avenue for research into breast cancer prevention. Regrettably, despite these promising results, funding for new estrogen studies has been limited since the release of the WHI results in 2002.
According to Dr. J. Manson, a researcher from Brigham and Women’s Hospital involved in the WHI, these results are intriguing but still in the preliminary stages. The true value lies in developing new strategies for preventing breast cancer and further exploring why estrogen, on its own, appears to reduce the risk of this disease.
Some experts speculate that estrogen therapy may protect women from breast cancer by blocking the effects of a woman’s naturally occurring estrogen, akin to how the drug tamoxifen functions as an estrogen blocker.