Many women are hesitant to take hormone replacement because they fear that it will increase their chances of developing breast cancer. Up to this time, after so much medical research, this remains a complicated and controversial issue, especially as we are talking about the most common cancer in the Western world. Statistical data shows that breast cancer affects one in every thirteen women by the age of seventy-five and one in eight women who have a family history of this disease. In some cancerous tumors, a substance known as estrogen receptor is present, which means the possibility that cancer may be promoted by estrogen therapy.
The incidence of breast cancer continues to rise progressively through life, so one certainly would not want to do anything during midlife that might further increase this risk. Women who are most at risk of developing breast cancer include those who have never given birth or who are over thirty when they had their first children, obese women, women who went through puberty early, or went through menopause late (after the age of forty -four) and those with a family history of breast cancer. A common feature among these factors is a prolonged and constant exposure to estrogen from the ovaries. Women who consume high fat and low fiber diets have high blood levels of estrogen than women on low-fat, high-fiber diets and they also have much higher incidence of breast cancer, so it seems that we have yet another possible link between estrogen and breast cancer.
Notwithstanding these theoretical indications, however, of nearly thirty studies determining the correlation between estrogen replacement and breast cancer, the major have failed to indicate a definitive for or against this form of treatment. Data is contradictory in that studies linking estrogen therapy to breast cancer also show that women on estrogen who developed breast cancer had survival rates that were significantly better than that of women not on estrogen.
Although studies that show an increased risk of breast cancer are only population studies that surveyed women on hormone replacement therapy, rather than rigorously designed clinical trials comparing the experience of a group of women taking this treatment from a group taking a placebo, they still should make a doctor cautious about prescribing a high dose or prolonged use of estrogen replacement therapy to a woman with a known high risk of breast cancer. In such a case, if estrogen therapy is deemed extremely necessary, it is wise to use smaller or intermittent doses of estrogen replacement therapy. This is reassuring for women who want to take estrogen replacement for only a short time.
All in all, with hormone replacement therapy of less than five years' duration, there is no increase in the incidence of breast cancer. The incidence may increase after ten to fifteen years of hormone replacement and this increase appears to be approximately 30 percent. Furthermore, while it appears that the incidence of breast cancer may increase with long term hormone substitution, women who get breast cancer while on hormone therapy are less likely to die from the disease.