The authors [of the study] estimate that, based on an increased risk of 30 percent, the excess number of breast cancer which would be caused by the use of estrogens by three million women would be 4,708 new cases of breast cancer and 1,468 breast cancer deaths. If the excess risk is 60 percent, as found in the high quality studies, there would be about 10,000 new cases of breast cancer and 3,000 deaths per year."

Women have now been exposed to both long-term hormone treatment in the form of the birth control pill and long-term hormone treatment in the form of estrogen replacement.

No one really knows what the combined effect might be on the intricate workings of the female reproductive system. There are several ongoing studies to evaluate that specific interaction, but results are not yet available.

In Britain, the Imperial Cancer Research Fund is to carry out a large study of the birth control pill and hormone replacement therapy. The study will look at the results of 40 previous studies involving more than 60,000 British women. It will compare 30,000 women with breast cancer to 30,000 women who are free of the disease.

Post-menopausal women who are moderately overweight may have a slightly higher risk of breast cancer because of the increased amount of estrogen hormone produced by fat tissues.

Women exposed to DES during pregnancy have an increased risk of breast cancer 20 years after exposure.

Weighing The Risks Versus The Benefits

So far, there have been no long-term studies on the effects of estrogen and progesterone on healthy post-menopausal women without low bone mass or coronary risk factors.

The first three year study on the effects of HRT on healthy women was completed in 1995. Known as PEPI or Progestin-Estrogen Prevention Intervention, the study looked at the effect of HRT on blood lipids, blood pressure, and insulin of healthy post-menopausal women.

According to the study results published in the Journal of the American Medical Association (Jan/95), there were 875 women studied between the ages of 45 and 64. The women were divided into five groups, no treatment, .625mg premarin alone, .625mg premarin plus 10mg Provera for 12 days, .625mg premarin plus 2.5mg Provera daily and .625mg premarin plus 2.5mg OMP for 12 days.

Systolic blood pressure increased slightly in all groups. Insulin levels tended to decrease for all groups. Estrogen alone had the most positive effect on blood lipids, but one third of women developed pre-cancerous changes of the uterus. Those on Provera regimens showed a slight increase in HDL, but OMP had the most positive effect on HDL. In all groups, except those women receiving no treatment, triglycerides increased 20 to 25 percent above baseline.

However, woman on no treatment showed an average of a ten percent increase in fibrinogen, a risk factor for heart disease, while women in the treatment groups showed little change. Longer and more detailed studies involving large numbers of women are now underway.

One of them, a large ten year clinical trail involving 140,000 women, known as the Women's Health Initiative was authorized by the National Institute of Health in the United States. Among other issues, it will study the effects of estrogen therapy on the rate of heart attacks, breast cancer, fractures and death.

The long-term effects of taking estrogen are unknown. The risk of breast cancer is still an unsettled and unsettling question.

Recently, a long-term U.S. study published in the New England Journal of Medicine (Jun/95), showed that women receiving HRT or ERT for 6 or more years beyond menopause had a 40 percent increase in breast cancer risk. Commented the principal author of the study, Dr. Graham Colditz: "If a woman uses [hormones] long-term and stops, within two years, the risk goes back to that of a woman who never used the hormones."

Another alarming statistic recently came to light in 1995. A study of 240,000 women sponsored by the American Cancer Society found that those who took estrogen for at least six years had a 40 percent increased risk of fatal ovarian cancer.

Some doctors believe that the increased risk for uterine, ovarian and breast cancer caused by taking estrogen could be offset by decreasing deaths due to bone fractures and heart disease.