The Confusion over Estrogen Therapy and Breast Cancer

Is estrogen therapy good or bad for avoiding heart disease or cancer?  The reports from different studies make it difficult to work this out, and many women may throw up their hands in confusion.  Indeed, a New York Times columnist has asked the medical profession to “please make up its mind” about the issue.  Fortunately, clarification comes from an expert writing in the journal Cancer Prevention Research; here’s a summary of our present knowledge of the relationship between estrogen use and breast cancer.    

Postmenopausal women who have had a hysterectomy (surgical removal of the uterus) and who are given estrogen replacement have a decreased incidence of breast cancer.  Although estrogen usually stimulates breast cancer growth, when there’s been prolonged deprivation of estrogen the environment is right for extraneous estrogen to cause death of breast cells – this has been seen in lab cell-culture experiments. 

The unexpected effect of estrogen in hysterectomized women (decreasing breast cancer) is explained as follows: if breast cancer cells are deprived of estrogen, most of them die off, and then cells come back that can grow with a minimum of estrogen.  The same happens with anti-hormone therapy, like tamoxifen or relafine.  If estrogen is then made available, the cells die.

The practical results of this understanding of the effects of estrogen on breast cancer cells will now be evaluated by cancer physicians.  For once, it’s good to report that the findings from major studies do not contradict each other – this is not always the case!