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The National Heart, Lung, and Blood Institute (NHLBI) stopped the Women's Health Initiative (WHI) estrogen plus progestin study early due to an increased risk of invasive breast cancer compared to placebo. The combination also suggested a lack of overall benefit.
Estrogen is a natural hormone produced mainly by the ovaries. After menopause, the ovaries produce lower levels of estrogen and progesterone. When natural menopause is complete - usually age 45-55 - hormone output significantly decreases. Hormone therapy was approved for relief of menopausal symptoms and prevention of osteoporosis. Long-term use has been thought to prevent chronic conditions, especially heart disease. Estrogen is indicated for the treatment of moderate to severe vasomotor symptoms (hot flashes) associated with menopause, the treatment of vulvar and vaginal atrophy, and the prevention of osteoporosis. Progestins were added to therapy when estrogen alone showed an increased risk of endometrial cancer in women with an intact uterus. Since the mid-1980s the combination of estrogen and progestin use has increased.
The WHI trials are focused on the risks and benefits of strategies that could potentially reduce the incidence of heart disease, breast and colorectal cancer, and fractures in postmenopausal women. The WHI is broken into estrogen only, estrogen plus progestin, and placebo groups. A total of 16,608 women were enrolled in the estrogen plus progestin and placebo groups. The estrogen plus progestin group was the only one that stopped their study medications. The estrogen only group is still being evaluated.
What the trial showed with combination
therapy:
· The absolute risk of harm to individual women is very small. The risk of harm means that 10,000 women taking the combination therapy for one year will develop the following differences in events when compared to women not on therapy :
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§ 7 more coronary heart disease events (heart attacks--most were non-fatal)
§ 8 more strokes
§ 8 more cases of invasive breast cancers
§ 18 more cases of venous thromboembolism
§ 6 less cases of colorectal cancers
§ 5 less hip fractures
§ all outcomes combined produces 19 more events per 10,000 women treated versus those not on therapy
· This study does not distinguish the effects of estrogen from those of progestin
· This study does not distinguish the effects of one type of estrogen or progestin from another
· What is still not known:
§ Does risk increase due to higher doses, longer duration, or both?
§ Does switching regimens of estrogen or estrogen plus progestin affect risk?
§ Does the form of estrogen (tablet, patch, shot, cream) affect risk?
What should you do if you are taking estrogen plus progestin?
· Do not stop taking your medication abruptly
· Take this opportunity to discuss the risks and benefits of therapy with your physician
· Risk increases the longer the combination is taken
· There are several options for osteoporosis protection
· The combination should not be used to prevent chronic diseases
Reference:
www.nhlbi.nih.gov/whi
The Women's Health Initiative Study Group. Risks and Benefits of Estrogen Plus Progestin in Healthy Postmenopausal Women. JAMA. 2002; 288:321-333.
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