About DES (Diethylstilbestrol): DES and Cancer
Navigating the Complex Landscape of Cancer Risks: Insights into DES Exposure and Breast, Cervical, Skin, Testicular, and Prostate Cancers
Breast Cancer
Breast cancer has many risk factors, and DES exposure is one of them.
DES Mothers
The breast cancer risk for DES Mothers is approximately 30–50% higher than for women not given DES during pregnancy.
DES Daughters
Previous research showed a small increase in breast cancer risk among DES Daughters throughout their lifetime, although this population was considerably younger at the time of those early studies The latest analysis published in 2017 by researchers from the National Cancer Institute found a 33% increase in breast cancer risk in DES Daughters in their 40s. The interesting finding was that when the findings were adjusted for risk factors, like smoking, the increased risk disappeared. This led the team to postulate that DES exposure could directly worsen risk factors, which would then indirectly lead to a greater incidence of breast cancer in that population.
The excess risk appears to begin lessening after age 50, even though breast cancer risk in the general population – independent of DES exposure – tends to increase with age. Read our report on this study in the VOICE Winter 2018.
Of note, a 2006 study found that no specific tumor type or gene mutation has been associated with breast cancer in DES Daughters. Rather, researchers suspect that prenatal DES exposure may increase the growth of any cells that develop into breast cancer. It is this potential for a more rapid growth rate that results in the increased risk for, and incidence of, breast cancer at an earlier age for DES Daughters. This study was reviewed in the VOICE Spring 2007 newsletter.
The additional breast cancer risk for DES Daughters should also be considered in decisions regarding hormone replacement therapy (HRT). When absolutely necessary, only the lowest dose of HRT should be used for a short period. This recommendation applies to all women, especially DES Daughters and DES Mothers.
An interesting question being examined by researchers with the National Cancer Institute DES Follow-up Study is whether bra cup sizes might help explain the link to breast cancer in DES Daughters. The thinking is that prenatal DES exposure may increase the total number of mammary gland cells formed during development — hence larger bra cups. An initial study published in 2013 found support for the hypothesis that in utero DES exposure may result in greater mammary mass, which has been shown inconsistently in studies to raise the risk for breast cancer.
As a result, DES Action USA encourages DES Mothers and Daughters to remind their healthcare clinicians of their increased breast cancer risk and discuss an appropriate screening regimen. For most, it means annual mammograms coupled with annual clinical breast exams. Also, all women should pay attention to their breasts and alert their doctors if any changes are noticed.
Clear Cell Adenocarcinoma (CCA) of the Vagina and Cervix
The risk is small for this rare cancer, estimated at 1 in 1,000 women exposed to DES in utero.
It was once thought DES Daughters over age 30 were no longer at risk, but we now know CCA is a lifelong concern. A large study from the Netherlands followed 12,091 DES Daughters from 1992 to 2008 (most DES Daughters were born between 1961 and 1970). Although no elevation in overall cancer risk was found, the researchers demonstrated that the increased risk of CCA continues beyond 40 years of age. Cases have been reported in Daughters older than 50, when CCA may also occur in the unexposed population.
Researchers are now watching for a possible spike in cases of post-menopausal DES Daughters. A population-based analysis done in 2012 by CDC researchers suggests an elevated CCA risk for DES Daughters as they age. Studies are underway, but at this point, there does not appear to be an upper age limit for this cancer in DES Daughters.
- Cervical cancer vaccine
The cervical cancer vaccine currently available in the US does NOT protect against the type of cancer linked to DES exposure, which is clear cell adenocarcinoma (CCA) of the cervix and vagina. The vaccine does provide protection against the more common types of cervical cancer and genital warts that are caused by human papillomavirus (HPV) infection.
Melanoma (Possible)
Several studies looking at the overall risk of cancer in DES Daughters have come up with conflicting results regarding melanoma. In a US study published in 1998, researchers surveyed 4536 women with documented in-utero DES exposure, following them for 16 years, and found no increased risk of melanoma.
However, in the previously mentioned 2010 study of 12,091 DES Daughters in the Netherlands, a slight increase was observed in the risk of melanoma diagnosed before age 40. This finding has not been replicated in subsequent studies looking at overall cancer risk for DES Daughters and Sons.
Pancreatic Cancer (Possible)
The 2017 DES Combined Cohort Follow-up study results pointed to an increased risk of pancreatic cancer in DES Daughters. But when the findings were adjusted for other factors, the risk normalized. The researchers recommended further investigation and close follow-up for any signs or symptoms. Read the VOICE Winter 2018 for more specific information on their outcomes.
Testicular Cancer (Potential)
No DES-specific testicular cancer has been found. However, undescended testicles, one of the congenital abnormalities linked to DES exposure, are known to predispose men to testicular cancer. Therefore, DES Sons and Grandsons, who have a higher rate of this anomaly, might be considered a high-risk group. All men should practice testicular self-exam regularly.
Prostate Cancer (Possible)
DES Sons are reaching or are in the age range when prostate cancer may occur, but a recent study reports no increased incidence of prostate cancer in DES Sons. That said, animal studies point to the possibility of a heightened risk for DES-exposed men, leading some researchers to speculate that DES Sons could be at higher risk and should pay attention to the possibility.