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What Is the Purpose of the WHI Study on Combination Hormone Therapy?
The long-term studies in the WHI were initiated because over the years a number of research studies presented a complicated picture of the risks and benefits of hormone therapy, and its continued use for prevention of cardiovascular diseases was controversial. This situation led the NIH to conduct a large clinical trial of the risks and benefits of hormone therapy. The WHI set out to examine the long-term effect of estrogen plus progestin on the prevention of heart disease and hip fractures, while monitoring for possible increases in risk for breast and colon cancer. The estrogen plus progestin regimen was given to women who have a uterus since progestin is known to protect against endometrial cancer, a known effect of unopposed estrogen. A separate study of estrogen alone in women who had a hysterectomy also was begun.
Why Were the Women in the WHI Estrogen Plus Progestin Study Told to Stop Study Pills at This Time?
In its most recent review of the study data, the WHI Data and Safety Monitoring Board saw an increased risk of breast cancer in women taking estrogen plus progestin. The Board also saw that the previously identified risks for heart attacks, strokes and blood clots to the lungs and legs had persisted. Therefore, in the judgment of the Board, the overall risks outweighed the benefits of taking estrogen plus progestin.
What Were the Main Findings in the WHI Study on Estrogen Plus Progestin?
The main findings show that compared to women taking placebo pills:
· The numbers of women who developed heart attacks, strokes, or blood clots in the lungs and legs were higher in women taking estrogen plus progestin.
· The numbers of women who had hip and other fractures or colorectal cancer were lower in women taking estrogen plus progestin.
· There were no differences in the number of women who had endometrial cancer (cancer of the lining of the uterus) or in the number of deaths.
What Are the Increased Risks for Women Taking Estrogen Plus Progestin?
For every 10,000 women taking estrogen plus progestin pills:
· 38 developed breast cancer each year compared to 30 breast cancers for every 10,000 women taking placebo pills each year.
· 37 had a heart attack compared to 30 out of every 10,000 women taking placebo pills.
· 29 had a stroke each year, compared to 21 out of every 10,000 women taking placebo pills.
· 34 had blood clots in the lungs or legs, compared to 16 women out of every 10,000 women taking placebo pills.
What Are the Reduced Risks for Women Taking Estrogen Plus Progestin?
For every 10,000 women taking estrogen plus progestin pills:
· 10 had a hip fracture each year, compared to 15 out of every 10,000 women taking placebo pills each year.
· 10 developed colon cancer each year, compared to 16 out of every 10,000 women taking placebo pills.
What Are the Conclusions From These Findings?
The main conclusions are:
· The estrogen plus progestin combination studied in WHI does not prevent heart disease.
· For women taking this estrogen plus progestin combination, the risks (increased breast cancer, heart attacks, strokes, and blood clots in the lungs and legs) outweigh the benefits (fewer hip fractures and colon cancers).
What Were the Actual Hormones That Women in the Estrogen Plus Progestin Study Were Taking?
Women who were randomized to receive active hormones were taking conjugated equine estrogens 0.625 mg each day and medroxyprogesterone acetate 2.5 mg each day.
This is the most commonly prescribed postmenopausal hormone therapy in the United States for women who have a uterus (used each day by more than six million women).
When Did the Increased Risk of Breast Cancer Become Apparent for Women Taking Estrogen Plus Progestin Compared to Women Taking Placebo Pills?
There was no difference in the development of breast cancer during the first four years between women taking estrogen plus progestin and those taking placebo pills. After that time, the numbers began to increase. After an average of 5.2 years, there was an increased risk of breast cancer in women taking estrogen plus progestin compared to those taking placebo pills.
Is There an Increased Risk of Breast Cancer in Women Taking Estrogen Alone?
There is no evidence of an increased risk for breast cancer in women taking active estrogen alone, compared to those taking placebo pills, even after an average of 5.2 years. We do not know whether the long-term effects will differ. The Data Safety and Monitoring Board will continue to review participants' health data every six months.
Is There an Increased Risk for Ovarian Cancer With Long-Term Use of Estrogen Alone?
An observational study of women who took estrogen alone found that women who used estrogen alone for 10 to 19 years were twice as likely to develop ovarian cancer as those who did not use postmenopausal hormones. (Absolute number was about 7 cases per 10,000 women years compared to 4.4 per 10,000 women years if estrogens were never used.) If women used estrogen for twenty years or longer, the number increased to 14 per 10,000 person years.
How Does This New Information Affect Women in the WHI Study of Estrogen Alone?
The Data and Safety Monitoring Board of the WHI will be reviewing the information about the risks for ovarian cancer and provide their input to the NIH. The NIH will also send letters to the study investigators updating them with information which they can discuss with study participants.
Do You Have Recommendations About Other Hormone Alternatives (Lower-Dose Estrogens, Micronized Progesterone, Natural Hormones)?
We cannot make specific recommendations about other hormone medications, such as different estrogens or progestins. We also cannot make recommendations about hormones women take in lower dosages or in different ways, such as patches instead of pills.
Further, without scientific clinical trial data, one cannot assume that alternative estrogen plus progestin treatments are any safer than those studied in WHI.
I am taking prescription hormones, what should I do?
We recommend that you talk with your health care provider about your individual health risk profile and the hormones you are currently taking.
Does This New Information Apply to Selective Estrogen Receptor Modulators (SERMS) or Phytoestrogens?
These preparations were not studied in the WHI Hormone Program, and therefore, we cannot make any conclusions about the risks or benefits of SERMs, such as raloxifene (Evista®) or tamoxifen (Nolvadex®) or phytoestrogens.
How Does All of This New Information Affect My Decision to Use HRT for Relief From Hot Flashes, Sleep Problems and Mood Swings?
The WHI and the observational studies on the risk of ovarian cancer were long-term studies that were not meant to address the shorter-term use of HRT. Thus, the information from these studies should be used by women considering use of HRT for longer than three or four years.