A new study finds women with breast cancer should stop using hormone replacement therapy (HRT) as soon as they are diagnosed. The study, to be published in the journal Cancer, says stopping HRT appears to lead to tumor regression prior to surgery.
HRT, composed of estrogen with or without progesterone, provides relief to symptoms associated with menopause, such as flushing and mood swings. However, its use has been associated with an increased risk of breast cancer. Tumors linked to HRT are typically slow growing and estrogen receptor (ER) and progesterone receptor (PR) positive. They are generally treatable with the use of anti-estrogen therapies called selective estrogen receptor modulators (SERMs), such as tamoxifen or raloxifene, or with aromatase inhibitors, such as letrozole and anastrozole.
While HRT is contraindicated in breast cancer survivors, at what point breast cancer patients should stop HRT has been unclear. Some studies have suggested that HRT use does not affect a patient's prognosis. However, in their new study, a team of investigators led by Professor N.J. Bundred of the University Hospital of South Manchester (United Kingdom) evaluated women diagnosed with breast cancer who were taking HRT, to see whether withdrawing HRT after diagnosis of breast cancer and before surgery could affect the production of proteins associated with tumor growth.
In the hormone-sensitive tumors of women who stopped HRT before surgery, the team observed a reduction in cellular proliferation. They also found a decrease in cyclin D1, a stimulator of cell division and an increase in p27 (KIP-21), an anti-tumor protein that normally stops cell division and growth. Progesterone receptor levels dropped, which indicates the loss of external estrogen stimulus.
The authors conclude, "this study confirms that ER positive breast cancer responds to HRT (estrogen) withdrawal and therefore HRT should be discontinued at diagnosis and its subsequent use of HRT in women with ER positive cancers should be with extreme caution."
Cancer, December 15, 2003