Breast cancer in DES-exposed mothers, 1980

Breast cancer in mothers given diethylstilbestrol in pregnancy

1980 Study Abstract

Reports in the popular press have suggested that exposure to diethylstilbestrol (DES) is followed by an abnormally high incidence of breast cancer. The reports were based on a reanalysis of data not considered ominous originally; and both data and analyses are summarized here.

Preliminary data from the Mayo Clinic Center of the National DESAD Project (DESAD = DES plus Adenosis) bearing on the occurrence of breast cancer in women given DES (diethylstilbestrol) during pregnancy are reported. Data from 408 DES-exposed women were collected in a follow-up study. 8 cases of breast cancer were confirmed in the group. This compares with an expected rate of 8.1 for parous women in that county. These preliminary data do not show an excess of observed over expected cases of breast cancer among a DES-exposed population.

A previous case-control study at the Mayo Clinic designed to determine any association between breast cancer and antihypertensive therapy had found a breast cancer rate of 10% in the DES-exposed portion of the group and 12% in the controls, also denying any DES association with breast cancer causation.

It is pointed out that an earlier study at the University of Chicago which did find an association between DES usage and breast cancer had utilized higher doses of DES than the current study at Mayo.

There is a clear need for further research into the association between DES usage and breast cancer, taking into account dosage and duration of therapy. Excess risk, if it does exist, seems to concentrate in the under-50 age group.



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