Breast Cancer Risk From Diethylstilbestrol (DES)

Diethylstilbestrol (DES) was a manufactured nonsteroidal estrogen that is now known to be a carcinogen (cancer-causing chemical). DES increased the risk of breast cancer in pregnant people who took the drug. It also increases the risk of breast cancer in the children assigned female at birth of people who took it while pregnant with them.

DES is no longer produced. It was widely prescribed worldwide to prevent pregnancy loss from the mid-1940s through the early 1970s. DES was also prescribed to stop lactation, as emergency contraception, and to reduce menopausal symptoms.

In 1971, researchers found an association between prenatal exposure to DES and the development of clear cell adenocarcinoma (CCA) during puberty in children of people who took the drug while pregnant with them. CCA is a type of cancer that affects the vagina and cervix.

The Food and Drug Administration (FDA) halted prescribing DES to pregnant people shortly afterward. DES is now known to be an endocrine disruptor with the potential to cause breast cancer, infertility, and other conditions in exposed individuals and their future generations.

Not everyone exposed to DES will get cancer or other health conditions. However, it is important to know and understand the potential risk you and your children may face if you or your birthing parent took DES during pregnancy.

This article will discuss the possible complications of DES exposure, including breast cancer. It will also supply a list of DES drugs and information on assessing your potential risk of exposure.

Fast Facts About DES

These are facts about DES:

• DES is a synthetic type of estrogen. Estrogen is a sex hormone.
• DES was prescribed from the 1940s through the early 1970s to prevent pregnancy loss and other pregnancy complications.
• In 1971 it was determined that DES exposure in utero (before birth) could cause cancer of the vagina during puberty in DES children. DES was no longer recommended to pregnant people in the United States shortly after this finding.
• Five to 10 million people in the United States were exposed to DES, including pregnant people who took the drug and their children. The exact number of affected people is not known.
• DES is now known to be a carcinogen and an estrogen disruptor. Estrogen disruptors are chemicals that negatively impact the endocrine system.
• DES exposure does not increase the risk of getting all types of cancers.
• People who took DES have a modestly increased risk of getting and dying from breast cancer.
• DES children assigned female at birth are at an increased risk for breast cancer, pancreatic cancer, clear cell adenocarcinoma, and cervical precancers.
• DES children assigned female at birth may experience problems with fertility and pregnancy, including ectopic pregnancy (a non-viable pregnancy that implants in a place other than the uterus), preeclampsia (high blood pressure and signs of liver or kidney damage in pregnancy), premature birth, pregnancy loss, and early menopause.
• DES children may be born with a T-shaped uterus, an irregularly-shaped cervix, and other structural anomalies of the reproductive organs.
• DES children may have an increased risk for testicular cancer, although this has not been definitively proved.
• DES children of any sex or gender may have an increased risk of high cholesterol, coronary artery disease, hypertension, and heart attack. 
• DES grandchildren are currently studied to determine their risk for conditions including cancer and infertility.
  

Possible DES Complications 

Several potential complications of DES exposure in utero may occur in people of any sex, such as:

• Increased risk of cardiovascular disease and events such as heart attacks
• Increased risk for pancreatic disorders such as pancreatitis

In Utero Exposure in DES Children Assigned Female at Birth

The National Cancer Institute (NCI) Combined DES Cohorts Follow-Up Study identified or confirmed potential DES complications that specifically affect DES children assigned female at birth. These include certain types of cancer and issues with fertility and pregnancy, including negative pregnancy outcomes.

When compared to the risk level of the general population, these complications include:

• Elevated risk of breast cancer
• Elevated risk of clear cell adenocarcinoma
• Elevated risk of infertility
• Loss of pregnancy before the 20th week of gestation
• Preterm delivery
• Neonatal death (death of the infant within the first 28 days of life)
• Stillbirth: pregnancy loss at or after the 20th week of pregnancy
• Ectopic pregnancy
• Preeclampsia
• Early menopause: cessation of menstruation before age 45

DES Children Assigned Male at Birth

The NCI study identified or confirmed fewer risks from in-utero DES exposure for people assigned male at birth than for people assigned female at birth. These include an increased risk for testicular cancer, although this side effect has not been definitively proven. Infertility was not determined to be a side effect.

An increased risk for epididymal cysts (a noncancerous fluid-filled pocket in the sperm tube) has been identified.

The risk for certain urogenital anomalies has been found in some studies:

• Undescended testicles (cryptorchidism)
• Hypoplasia (smaller than usual size) of the penis
• Hypospadias (the opening of the urethra is not at the tip of the penis)
  

DES Grandchildren

Researchers are currently studying the third generation of DES-exposed children. Because they're still young, no conclusive information exists yet. The NCI study has identified several potential areas of concern in DES grandchildren assigned female at birth:

• Elevated risk of infertility
• Potential for skipped periods (amenorrhea)
• Potential for irregular periods
• Potential for ovarian cancer (this finding is only based on the experiences of three DES granddaughters)
  

DES grandchildren may have a slightly higher risk for hypospadias. In children born with this condition, the opening of the urethra is not located at the tip of the penis.

List of DES Drugs

DES was widely manufactured in the United States and abroad under scores of different product names. It was made available in pill form and as a cream or vaginal suppository. DES was also included as an ingredient in nonsteroidal estrogen-androgen and estrogen-progesterone combinations.

Product names include but are not limited to:

• Benzestrol
• Comestrol
• Desplex
• Diestryl
• Digestil
• Estrobene
• Estrosyn
• Fonatol
• Gynben
• Hexestrol
• Microest
• Nulabort
• Orestrol
• Restrol
• Synestrin

Assessing Your Risk 

DES was widely prescribed to millions of people. Not everyone who was exposed to the drug is aware of it. If you're not sure if you or the person who gave birth to you took DES, there are several things you can do to try and find out.

If you were pregnant between 1938 and 1971, try to remember if you were prescribed any medications during your pregnancy. This may be more likely if you had a history of pregnancy loss.

If you were pregnant in a country other than the United States, keep in mind that DES continued to be prescribed elsewhere until the late 70s or early 80s, based on the country.

If possible, try to locate your medical records. You can try to contact your healthcare provider's office if the practice still exists. If you gave birth in a hospital, they may have your records. Call or write to the facility to see if they keep OB/GYN records on hand for people they treated in the past.

If you hit a wall, try your local health department. They may have copies of old medical records from closed practices on hand. Reaching out to your pharmacy from that time may also be helpful.

If you suspect that the person who gave birth to you took DES and you are in communication with them, try to support them in this search. If that is not possible, it may be hard to access their records due to confidentiality laws. However, it may be worth a try.

Children who were born to people who took DES during their pregnancy often show anatomical signs that make getting a diagnosis easier. Talk to a healthcare provider and ask them if your reproductive organs resemble those of DES-exposed children.

Preventable Risk Factors 

Have regular medical exams, whether or not you're able to definitively determine your DES exposure. Let your healthcare provider know you may have been exposed to DES.

Getting annual mammograms is especially important for people with breasts. If you have dense breasts, your healthcare provider may also recommend annual sonograms in addition to mammograms.

Other ways to reduce your risk for breast cancer and other types of cancer include:

• Maintain a healthy weight.
• Exercise and be physically active.
• Don’t drink alcohol to excess.
• Don’t smoke cigarettes or use nicotine products.
  

Summary

Diethylstilbestrol (DES) was a prescribed medication that was given to pregnant people from the 1940s through the early 1970s. At that time, it was thought that DES could reduce the risk of pregnancy loss.

During the early 1970s, research determined that DES was a carcinogen and potentially dangerous for pregnant people to take. Millions of people had already been prescribed the drug.

DES moderately increases the risk of getting and dying from breast cancer in people who took it. Their children may also have an increased risk of certain types of cancer and other health conditions.

A Word From Verywell

If you took DES, you may feel angry, upset, or guilty. Everyone should be able to trust the prescribed medications they are given. It's not your fault you took a potentially dangerous drug. Neither your healthcare provider nor you fully understood the risks.

If you think you may have been exposed to DES in utero, you may also feel angry, scared, and confused. It's important to remember that DES exposure does not ensure bad outcomes. Your risk for breast cancer and other health conditions may be higher than the general population's, but that doesn't mean you or your children will get cancer, infertility, or other side effects.

The best thing you can do is get regular medical checkups to keep an eye on potential complications. Treatments are available for many DES side effects. Early diagnosis is your best bet for ensuring the best possible outcome.