Risks of Hormone Replacement Therapy

For years, many women with, or at risk for, osteoporosis have been prescribed HRT or ERT. HRT and ERT provide a number of benefits, but doctors are learning more and more about the risks associated with taking these medications. Recent findings from the Women's Health Initiative (WHI) study have shown that taking HRT for extended periods of time can increase a woman's risk of breast cancer and cardiovascular disease. Another recent study, this one sponsored by the National Cancer Institute, found that ERT could increase the risk of ovarian cancer when taken long-term.

Cancer risks

The WHI study recently demonstrated that HRT (estrogen plus progestin) is associated with a small increase in the risk of breast cancer. This increase in the risk for breast cancer is somewhat controversial; some studies conclude that a risk exists, while others find no increased risk. Evidence indicates that taking HRT for more than 5 years can increase the risk of breast cancer. It is still not known whether estrogen alone carries the same risk. If a woman is concerned about the risk of breast cancer, she should talk to the doctor about her individual lifetime risk. If taking HRT, monthly breast self-exams should be performed and the doctor should be contacted immediately if any unusual lumps or discharge is noted. Women who are aged 40 years or older should be sure to have a yearly mammogram and manual breast exam by a doctor.

A large study from the National Cancer Institute (NCI) has recently indicated that long-term use of ERT may be associated with a slight increase in the risk of ovarian cancer, especially if it is taken for 10 years or more. It is not yet clear whether HRT has a similar risk.

Cardiovascular risks

Taking HRT can increase the risk of cardiovascular problems such as stroke, heart attack, and blood clots. The risk of heart attack and blood clots increases in the first year of taking HRT, while the risk of stroke gradually increases after taking HRT for 2 or more years.

Whether estrogen alone (ERT) carries the same risks is unclear. The ERT portion of the WHI study is still being conducted, with an expected conclusion in 2005. Other smaller studies have found that ERT may provide some cardiovascular benefits. However, because of the risk of uterine cancer, women with an intact uterus should not take estrogen alone.