Higher Breast Cancer Risk Found for DES Daughters
Women whose mothers took DES, a synthetic estrogen, while pregnant have nearly double the risk of breast cancer, according to a report in the journal Cancer Epidemiology, Biomarkers and Prevention.
Called DES, diethylstilbestrol was prescribed from 1938 through 1971 to prevent miscarriage and other pregnancy complications.
During that time, as many as 10 million American women took DES during pregnancy, the Centers for Disease Control and Prevention (CDC) estimates.
The study compared women exposed to DES in utero (in the uterus) to a group of comparably aged women who were not exposed to the excess hormone levels.
"Women who were exposed to DES have been wondering about this for a long time," says the study's lead author, Julie Palmer, Sc.D., a professor of epidemiology at Boston University's School of Public Health.
"We found the risk of breast cancer was about two times as high in the exposed women compared to unexposed women among those 40 years and older," notes Dr. Palmer.
Although research published in 1953 refuted the notion that DES could prevent the loss of pregnancy or pregnancy difficulties, physicians still continued to prescribe the medication.
In 1971, the US Food and Drug Administration (FDA) advised physicians to stop prescribing DES because it was linked to a rare form of vaginal and cervical cancer - clear cell adenocarcinoma - in daughters of women who took DES while pregnant.
These women eventually came to be known collectively as "DES daughters," according to the CDC.
Besides the increased risk of clear cell adenocarcinoma, being a "DES daughter" also increases the risk of reproductive tract defects, such as a T-shaped uterus, infertility, and pregnancy complications, such as ectopic pregnancy or pre-term birth, according to the CDC.
Boys born to mothers who took DES may experience abnormal, though non-cancerous, growths on their testicles.
Previous research had suggested that prenatal hormone levels of DES may affect the risk of breast cancer later in life. And women who took DES have higher rates of breast cancer.
So, the researchers behind the new study wanted to assess what the actual risk of breast cancer was for women exposed to DES in utero.
The scientists recruited 4,817 women who had been exposed to DES in utero and 2,073 women born in the same time period, but who had not been exposed to the medication.
Most of the women in both groups were born in the 1950s, and nearly all were Caucasian.
During 2001 to 2003, the women were sent questionnaires, and 102 women - 76 in the DES-exposed group and 26 in the control group - reported a diagnosis of breast cancer.
After compensating for other breast-cancer risk factors, the researchers found that women who were exposed to DES in utero had a 91 percent higher risk of breast cancer after age 40, and a three-fold increased risk of breast cancer after age 50, when compared to women not exposed to the medication.
"These women received a much higher exposure to synthetic estrogen than would normally be there during a regular pregnancy," explains Dr. Palmer.
She theorizes that the extra estrogen spurs the development of additional breast stem cells, and because there are a greater number of breast stem cells, there is an increased risk of cancer.
Dr. Jay Brooks, chairman of hematology and oncology at the Ochsner Health System in Baton Rouge, La., says, "This is an interesting study that shows we still don't know all of the long-term effects on women who took DES and their female offspring.
"This is important, but should be kept in perspective," he adds. "While it is an increased risk, it's along the same order of escalation of risk as having a family history of breast cancer or of not having a child by the age of 30."
Dr. Brooks says if women - all women, whether exposed to DES or not - wanted to decrease their risk of breast cancer, they should maintain a normal weight, or lose excess weight.
Dr. Palmer adds that some research has shown that regular physical activity may be helpful in reducing your risk of breast cancer.
Women who know they were exposed to DES in utero should carefully discuss the use of post-menopausal hormones with their physician, she suggests.
Dr. Palmer also notes that all women should have regular mammogram screenings to detect breast cancer in its earliest stages.
Depending on what additional risk factors women exposed to DES may have, Dr. Brooks says women might want to discuss the potential risks and benefits of using the medications tamoxifen or raloxifene, because these medications block the action of estrogen, which can fuel some breast tumors.
Always consult your physician for more information.
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Higher Breast Cancer Risk Found for DES Daughters
Over Time Much Is Learned
DES Daughters Should Monitor Closely
NCI Facts on DES
Online Resources
It has been estimated that 5 to 10 million people were exposed to DES during pregnancy, according to the National Cancer Institute (NCI). Many of these people are not aware that they were exposed.
A woman who was pregnant between 1940 and 1971 and had problems or a history of problems during pregnancy may have been given DES or a similar medication.
Women who think they used a hormone such as DES during pregnancy, or people who think that their mother used DES during pregnancy, can contact the attending physician or the hospital where the delivery took place to request a review of the medical records.
If any pills were taken during pregnancy, obstetrical records should be checked to determine the name of the medication. Mothers and children have a right to this information.
However, finding medical records after a long period of time can be difficult.
If the physician has retired or died, another doctor may have taken over the practice as well as the records.
The county medical society or health department may know where the records have been stored.
Some pharmacies keep records for a long time and can be contacted regarding prescription dispensing information.
Military medical records are kept for 25 years. In many cases, however, it may be impossible to determine whether DES was used.
It is important for women who believe they may have been exposed to DES before birth to be aware of the possible health effects of DES and inform their doctor of their exposure.
It is important that the physician be familiar with possible problems associated with DES exposure, because some problems, such as clear cell adenocarcinoma, are likely to be found only when the physician is looking for them. A thorough examination may include the following:
Pelvic examination - a physical examination of the reproductive organs. An examination of the rectum also should be done.
Palpation - As part of a pelvic examination, the physician feels the vagina, uterus, cervix, and ovaries for any lumps. Often palpation provides the only evidence that an abnormal growth is present.
Pap test - A routine cervical Pap test is not adequate for DES-exposed daughters. The cervical Pap test must be supplemented with a special Pap test of the vagina called a “four-quadrant” Pap test, in which cell samples are taken from all sides of the upper vagina.
Iodine staining of the cervix and vagina - An iodine solution is used to temporarily stain the linings of the cervix and vagina to detect adenosis (a noncancerous but abnormal growth of glandular tissue) or other abnormal tissue.
Colposcopy - In colposcopy, a magnifying instrument is used to view the vagina and cervix. Some doctors do not perform colposcopy routinely. However, if the Pap test result is not normal, it is very important to check for abnormal tissue.
Biopsy - Small samples of any tissue that appears abnormal on colposcopy are removed and examined under a microscope to see whether cancer cells are present.
Breast examinations - Researchers are studying whether DES-exposed daughters have a higher risk of breast cancer than unexposed daughters; therefore, DES-exposed daughters should continue to follow the routine breast cancer screening recommendations for their age group
Always consult your physician for more information.
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