Confirmed Health Effect: Breast Cancer
Studies show that women prescribed DES while pregnant have a slightly increased risk for developing breast cancer (Colton et al., 1993; Greenberg et al., 1984; Titus-Ernstoff et al., 2001). The most recent and definitive study to date (Titus-Ernstoff et al., 2001) involved an examination of the medical records of 4,000 women who were exposed and 4,000 women who were not exposed to DES. The study detected a modest association between DES exposure and breast cancer risk, with a relative risk of about 1.3. In other words, 16% of women prescribed DES during pregnancy developed breast cancer, in comparison with 13% of women not prescribed DES. Therefore, it is estimated that one in six women who were prescribed DES will develop breast cancer, whereas one in eight women in the general population will develop the disease.
Importantly, the study found no evidence that DES exposure during pregnancy is related to an increased risk of other cancers, including ovarian or endometrial cancer (Titus-Ernstoff et al., 2001).
Screening and Treatment
Breast Cancer Screening
It is essential to talk with patients about how often to check for breast cancer. Screening recommendations for women not prescribed DES during pregnancy and women prescribed DES during pregnancy are the same; both groups of women need to have clinical breast examinations and screening mammograms every one to two years, starting in their forties.
Hormone Replacement Therapy
Women who were exposed to DES while pregnant may be concerned about whether they should receive hormone replacement therapy (HRT) because of the exposure that they would incur from additional estrogen. Although taking DES while pregnant and HRT have both been independently associated with an increased risk of breast cancer, research to date has not found an interactive effect between DES exposure and HRT (Titus-Ernstoff et al., 2001).
Researchers are currently examining the effects of DES exposure on the grandchildren of women prescribed DES while pregnant. Some animal studies have shown increased tumor rates in third-generation mice as they age. A small clinical study did not find evidence of structural reproductive abnormalities in 28 DES granddaughters (Kaufman et al., 2000). A larger survey is under way to determine if there are increased risks of reproductive problems and cancer. The findings of Klip and associates (2002), who studied the sons of a Dutch cohort of women who had been exposed to DES in utero, suggested that these sons may have an increased risk of hypospadias; however, further study is necessary.
There are several DES resources for clinicians and patients.
DES Action USA
610 16th Street, Suite 301
Oakland, CA 94612
Voice: (510) 465-4011
Fax: (510) 465-4815
A national consumer organization representing DES mothers, daughters, and sons. Dedicated to informing the public and health professionals about the effects of DES and what can be done about them, and to promoting DES research. Offers physician referrals, special publications, and a quarterly newsletter (DES Action Voice).
DES Cancer Network
514 10th Street, NW
Washington, D.C. 20004-1403
Voice: (800) DESNET-4, (202) 628-6330
Fax: (202) 628-6217
Web site: www.descancer.org
A national network for DES-exposed women and men with a special focus on DES research advocacy, programs for DES-exposed people coping with cancer, and communication about DES issues. Offers information, peer support, medical referrals, and a newsletter (DES Issues).
DES Sons Network
DES Action/DES Sons Network
104 Sleepy Hollow Place
Cherry Hill, NJ 08003
Voice: (856) 795-1658
Fax: (856) 795-1658
A national network providing information and support for men exposed to DES before birth (DES Sons), and counseling for men with testicular cancer.
DES Third Generation Network
Mahwah, NJ 07430
An advocacy network designed to collect and share information about the health of children born to DES Daughters (women exposed to DES before birth [in the womb]) and DES Sons (men exposed to DES before birth [in the womb]).
National Cancer Institute
Cancer Information Service
M-F 9:00 a.m. to 7:00 p.m.
(800) 4-CANCER or (800) 422-6237
A national service providing free, accurate, up-to-date information on cancer to patients and their families, to health professionals, and to the general public.
Registry for Research on Hormonal Transplacental Carcinogenesis
Department of Obstetrics and Gynecology
The University of Chicago
5841 South Maryland Avenue
Mail Code 2050
Chicago, IL 60637
Voice: (773) 702-6671
Fax: (773) 702-0840
An international research registry of cancer patients with clear cell adenocarcinoma (CCA) of the vagina and/or cervix or other gynecologic cancer who may or may not have been exposed to DES or other synthetic hormones while in utero. A resource for clinicians and scientists, the Registry was established in 1971 to centralize data collection on CCA and enable us to learn more about the epidemiology and pathology of these tumors.
Nonsteroidal Estrogen-Androgren Combination
Vaginal Cream Suppositories with Nonsteroidal Estrogens
Source: National Cancer Institute. Exposure in utero to diethylstilbestrol and related synthetic hormones. JAMA 1976 Sept 6; 236 (10): 1107-1109.
Colton, T., et al. (1993). Breast cancer in mothers prescribed diethylstilbestrol in pregnancy. Journal of the American Medical Association, 269, 2096–2100.
Titus-Ernstoff, L., et al. (2001). Long-term cancer risk in women given diethylstilbestrol (DES) during pregnancy. British Journal of Cancer, 84, 126–133.
Kaufman, R. H., et al. (2000). Pregnancy outcomes in diethylstilbestrol-exposed offspring: Continued follow-up. Obstetrics and Gynecology, 96, 483–489.
Klip, H., et al. (2002). Hypospadias in sons of women exposed to diethylstilbestrol in utero: A cohort study. Lancet, 359, 1081–1082.