Research summary
August 2006
Research shows ‘DES daughters’ at increased risk of breast cancer after the age of 40 years
Summary
Researchers from the United States have found ‘DES daughters’, or women born to mothers who used the anti-miscarriage drug diethylstilbestrol during pregnancy, are at greater risk of developing breast cancer after the age of 40 years compared to women who were not exposed to the drug.
The researchers have reported in the August issue of the journal Cancer Epidemiology, Biomarkers & Prevention that DES daughters over the age of 40 are at nearly two times the risk of developing breast cancer, compared to unexposed women of the same age. The researchers also found this risk may be even greater for women aged over 50, but noted there were not enough women of this age in their study to make any firm conclusions.
The study found the level of breast cancer risk for an individual woman increased with increasing levels of exposure to DES. But the types of breast cancer discovered in the women exposed to DES were no more or less aggressive than is commonly seen in women with breast cancer who have not been exposed to the drug.
The ongoing study involved over 4800 DES daughters and 2000 unexposed women across the United States.
National Breast Cancer Centre comment
Diethylstilbestrol or DES is a synthetic oestrogen which was used in the past to prevent miscarriage. DES was used in Australia in the 1940s and 1950s and to a lesser extent, in the 1960s.
Exposure to DES has been already linked with the development of a rare cancer of the vagina and/or cervix (called clear cell adenocarcinoma) in the daughters of women who took the drug during pregnancy. DES daughters may also have structural abnormalities in the vagina, uterus or cervix, irregular menstruation, and an increased risk of miscarriage, ectopic pregnancy, infertility and premature birth.
Up until now there has been an identified small increase in breast cancer risk for the women who took DES (‘DES mothers’). This new US study is the first to suggest an increase in breast cancer risk for DES daughters.
The study findings suggest that women who were exposed to DES ‘in utero’ (DES daughters) have an increased risk of breast cancer at the ages at which breast cancer becomes more common.
DES daughters should inform their doctors of their exposure and should discuss their surveillance needs with their GP or gynaecologist. This is likely to include regular cervical and mammographic screening in relevant age groups.
The BreastScreen Australia program offers free mammographic screening for women aged 40 years and older and targets women aged 50-69 years.
Women of all ages should also know the normal look and feel of their breasts and report any changes to their doctor without delay.