Q. My mother took DES when she was
pregnant with me. I'm now 69, my daughter is 41, and we've both
had gynecological problems. What particular risks do we have
because of our DES exposure, and what can we do about them?
A. DES, or diethylstilbestrol, is a
synthetic estrogen that was prescribed in the 1940s, '50s, and
'60s to prevent miscarriage and premature delivery. In 1971, the
FDA issued a warning against its use in pregnant women after
researchers at Massachusetts General Hospital in Boston linked it
to a rare cancer of the vagina and cervix — clear cell
adenocarcinoma (CCA) — in the daughters of women who took the
drug while pregnant. Between 1938 and 1971, five to 10 million
people in the United States were exposed to DES, including women
who took the drug while pregnant (DES mothers) and the children
born of these pregnancies (DES daughters and DES sons).
Many studies have confirmed links between DES exposure and
various health risks. Most of these health problems also occur in
people who haven't been exposed to the drug, and it's difficult
to determine the cause in individual cases. But the research has
identified health issues that people exposed to the drug should
be on the watch for. Since 1992, the National Cancer Institute
has been monitoring DES-exposed (and unexposed) mothers and their
daughters and sons in a controlled investigation called the DES
Follow-up Study (www.desfollowupstudy.org).
The grandchildren of DES mothers have also been enrolled in a
third-generation study. Here is what we've learned from this
research about the health risks for DES-exposed women and men —
and the precautions (if any) that they should take:
DES mothers (women prescribed DES while pregnant) have a modestly
increased risk of breast cancer. The lifetime risk of breast
cancer in a DES mother is one in six, while the lifetime risk of
a woman who was not exposed to DES is one in eight. DES mothers
should tell their clinicians about the exposure. They should have
yearly clinical breast exams and regular mammograms (every one to
two years), and they should practice self-breast exam.
DES daughters (women exposed prenatally to DES) have a 40-fold
increased risk of CCA of the vagina and cervix, but even in this
group, the disease is extremely rare — one case per 1,000 to
2,000 exposed daughters. DES daughters are 2.5 times more likely
to develop breast cancer after age 40 than their unexposed
counterparts. They don't appear to be more vulnerable than
average to any other malignancy.
Prenatal DES exposure is also associated with several anatomical
irregularities of the reproductive tract, including a T-shaped
uterus, hooded cervix, abnormal vaginal tissue, and abnormalities
of the fallopian tubes. Many of these irregularities are
harmless, but they may contribute to pregnancy complications.
Compared with women who were not exposed to the drug, DES
daughters are at higher risk for ectopic (tubal) pregnancy,
miscarriage, and preterm delivery. They also have a slightly
increased risk of infertility.
Make sure your clinician knows you are a DES daughter. You should
have yearly gynecological exams, including Pap testing that takes
samples not only from the cervix but also from the surfaces of
the upper vagina. You should continue Pap testing even after a
hysterectomy. If your clinician detects any abnormalities during
an exam, she or he may want to evaluate the vagina and cervix
with colposcopy (inspection with a binocular-like magnifying
device and biopsy of areas that look abnormal). You should also
have yearly clinical breast exams and regular mammograms (every
one to two years) and practice breast self-exam.
DES sons (men exposed prenatally to DES) have an increased risk
of noncancerous epididymal cysts (growths on the testicles). A
few studies suggest that they are also more likely to be born
with undescended testes, a misplaced opening of the penis, or an
abnormally small penis, but the findings have been inconsistent.
DES grandchildren (sons and daughters of women and men exposed
prenatally to DES) do not appear to be at increased risk for
DES-related health problems, but research is just beginning.
There are no special screening recommendations. Nevertheless, the
exposure should be noted in their health records. The CDC has
compiled the latest information about DES in a booklet, DES
Update, which you can download at /DES_update.
— Martha K. Richardson, M.D.
Advisory board member, Harvard Women's Health Watch