Questions and answers about the health risks and benefits of Estrogen and Progestin 3 years after stopping randomized treatment

  1. What is the bottom-line message from this three year post intervention follow-up?
  2. What is noteworthy about this study and/or its findings?
  3. Are there surprises in these results that the investigators did not anticipate?
  4. Why is this information important to women?
  5. Does this study tell us why these findings occurred?
  6. Are there any recommendations based on the findings?

1. What is the bottom-line message from this three year post intervention follow-up?

The widely shared information about the use of hormone therapy with estrogen plus progestin is unchanged. These new results indicate that for prevention of chronic disease, the risks of estrogen plus progestin exceed the benefits.

2. What is noteworthy about this study and/or its findings?

The WHI is the only long-term trial of estrogen plus progestin in generally healthy post menopausal women. As a result, this scientific information about the health risks and benefits after stopping this form of hormone therapy in a standardized manner is new.

3. Are there surprises in these results that the investigators did not anticipate?

The WHI investigators did not expect to find an increased overall risk of cancer after stopping the estrogen plus progestin. At this point the follow-up period is short, but we continue to follow the health of WHI women. The WHI participants in this study have generously contributed their time and information so that we can better understand these trends by doing further analyses after continued follow-up.

The investigators did anticipate that some of the risks observed during the trial would gradually go away after stopping hormone therapy and that the risks of cardiovascular disease in particular would disappear rapidly. That is what we found.

The investigators also thought that the benefit for fractures might go away after stopping the intervention with estrogen plus progestin. Again, that is what was found.

The investigators expected that the greater risk of breast cancer in women previously on estrogen plus progestin might decrease, but would do so more slowly. These findings were not a surprise.

4. Why is this information important to women?

After the WHI trial was stopped in 2002, many women stopped taking estrogen plus progestin because of the increased risks of cardiovascular disease and breast cancer. These women need to know how stopping might affect their future health, and to have information to review with their health care providers in order to maintain their health.

5. Does this study tell us why these findings occurred?

Stopping hormone therapy removed one factor that increases the risk of cardiovascular disease in women. It is not clear why hormone therapy with estrogen plus progestin increased the risks during the trial, but likely explanations include a greater tendency for blood to clot and for inflammation to develop in the blood vessel walls.

We are not sure why the risks of cancer increased after stopping therapy. In part the increase was due to the disappearance of the previous apparent protection from colorectal cancer. Added to this was some continued greater breast cancer risk, and also some added risk of lung cancer. The continued follow-up of the WHI study participants will permit a more detailed study of the cancer findings.

Lastly, it is known that hormone therapy is beneficial for bone health and fractures, so the loss of protection after stopping therapy was expected and can be explained fairly well.

6. Are there any recommendations based on the findings?

This follow-up after stopping estrogen plus progestin use indicates higher levels of breast cancer, lung cancer, stroke, and death among those who had taken this therapy. Thus, there is a need for prevention efforts through healthy life style choices, risk factor control, and regular screening activities as recommended by health care practitioners.

Although increased risks for heart disease, stroke, and blood clots attributable to hormone therapy with estrogen plus progestin are no longer present after stopping hormone therapy, cardiovascular disease remains the leading cause of death among all women. Thus, women need to take action to prevent cardiovascular disease even after stopping hormone therapy. This includes making healthy lifestyle choices, having checkups for risk factors such as high blood pressure, high blood cholesterol, and diabetes, and treating these risk factors as needed.

If a woman stops hormone therapy, she loses some protection against fractures, so it is important that other steps are taken to prevent or reduce osteoporosis and fracture risk in consultation with a provider of health care. Women also should continue to monitor their risk for cancers (including breast cancer and lung cancer).

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