Diethylstilboestrol (DES)

• Daughters of DES - WHW Sept 1998
• DES and the risk of fatal breast cancer - WHW Jan 1997

Daughters of DES

September 1998 Women's Health Watch

A recent study reassured that women exposed to diethylstilboestrol (DES) while in utero are not at greater risk of cancers, others than the well-documented risk of clear cell adenocarcinoma (CCA) of the vagina and cervix.

The study consisted of 16 years' follow-up of 4536 DES-exposed daughters and 1544 unexposed daughters. The study showed that so far DES daughters have not experienced an increased risk for all cancers, or for individual cancers except for CCA. Breast cancer was no more prevalent among the DES daughters than among the other women.

The researchers say that as the exposed daughters were, on average, only 38 years old at last follow-up, continued surveillance is warranted to determine whether there is an increased risk during their menopausal years.
Ref: JAMA, 1998; 280: 630-34

DES and the risk of fatal breast cancer

January 1997 Women's Health Watch

Diethylstilbestrol, a potent synthetic oestrogen, was used between 1940 and 1970 for a range of conditions, -including prevention of miscarriage. For many years it has been known that DES caused genital tract abnormalities and cancers in the daughters of women who took it. For some time it has also been suspected that the mothers might face an increased risk of breast cancer but so far study results have been inconclusive.

The researchers in this study used the 676,526 participants in the Cancer Prevention Study II begun by the American Cancer Society in 1982 to see whether DES increased the risk of breast cancer.

After nine years of follow up, there were 1,574 fatal cases of breast cancer among the 501,536 eligible women.

When enrolled in the study women had been asked if they were ever given DES,3.9% of the women said they had. They were an average of 27 years old when they used it and the peak years of use were 1950-1956.

The researchers found that use of DES increased the risk of dying of breast cancer by just over one-third. The risk did not increase over time. The positive association was not seen in women who used DES before the age of 25 years but was seen at all other ages.
Ref: Am J of Epidemiology 1996; 144: 645-52