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A Single Dose Of This Medication May Help Lower Breast Cancer Risk
Breastfeeding may be over, but the changes it brings to your body don't stop overnight. After weaning, your breasts have to clear away much of the tissue they built to make milk.
Could helping that process along also help protect against breast cancer? Researchers are exploring the idea, especially for women with BRCA1 mutations, which raise breast cancer risk.
New research tested whether a single dose of cabergoline, a medication used to stop milk production, could help reduce breast tumors.
About the study
During pregnancy, breasts grow extra tissue to prepare for milk production.
After weaning, the body breaks down much of that tissue. Researchers suspected that if this cleanup doesn't go as planned, some abnormal cells could stick around. This may be especially important when BRCA1, a gene that may play a role in this tissue cleanup, isn't working properly.
To test the idea, researchers studied mice with faulty versions of BRCA1 and TP53, two genes linked to aggressive breast cancers.
After two pregnancies and nursing periods, some mice received one dose of cabergoline when they stopped nursing. Researchers then tracked tumor development and changes in breast tissue.
They also reviewed health records from nearly 15,000 women in Spain who had their first baby at age 30 or older, along with more than 690,000 women in Norway.
They compared breast cancer rates in women who took cabergoline after childbirth with rates in those who didn't.
Fewer tumors after a single dose
Cabergoline didn't stop every mouse from developing breast cancer, but fewer mice developed tumors after receiving it. Here's how the groups compared:
- Mice that received cabergoline after pregnancy and nursing: About 28% developed breast tumors
- Mice that had given birth and nursed but didn't receive cabergoline: About 59% developed tumors
- Mice that had never been pregnant: Nearly 89% developed tumors
Tumors also appeared later in the mice given cabergoline.
Researchers think the medication may help clear away leftover breast tissue, including abnormal cells that could contribute to cancer. However, it didn't reduce tumor development in mice that had never been pregnant.
The researchers also examined women's health records. When they combined data from Spain and Norway, women who took cabergoline after childbirth had about a 69% lower breast cancer risk.
On their own, the results were borderline in Spain and inconclusive in Norway, and the findings can't prove that the medication caused the lower risk.
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Why this matters for women with BRCA1 mutations
Women with BRCA1 mutations have a higher risk of breast cancer, and cancers diagnosed in the years after childbirth can be particularly concerning. Many preventive medications work by blocking estrogen, but they don't help prevent every type of breast cancer.
Cabergoline could offer a different approach by targeting how breast tissue changes after pregnancy.
Although pregnancy is linked to long-term breast cancer protection, risk can temporarily rise in the years after childbirth. Researchers want to know whether helping the breast clear away leftover tissue could make a difference during this window.
There are important limitations. The women in the study generally took cabergoline shortly after giving birth to stop milk production, while the mice received it after nursing ended.
Researchers also lacked details about how long the women breastfed and what types of tumors developed.
Clinical trials must establish whether cabergoline can safely lower breast cancer risk in humans.
What to discuss with your doctor
Cabergoline isn't an established breast cancer prevention treatment, so don't take it for this purpose outside medical guidance. This is early research. If you're concerned about your breast cancer risk, here are a few useful next steps:
- Know your family history: Tell your health care provider if close relatives have had breast cancer, especially at a young age. Ask whether genetic counseling or BRCA1 testing may be appropriate.
- Discuss your personal risk: If you carry a BRCA1 mutation or have a strong family history, ask which proven screening and prevention options are right for you.
- Ask about research opportunities: If you're pregnant, recently gave birth, or planning to wean, ask whether any clinical trials are investigating cabergoline and breast cancer prevention.
- Understand the medication's risks: Cabergoline can cause nausea, headaches, and dizziness. Researchers also say future trials should carefully screen for blood pressure problems during or after pregnancy, so discuss its risks with your health care provider rather than taking it for an unproven benefit.
The takeaway
Cabergoline helped reduce breast tumors in mice that had given birth, but it didn't eliminate the risk. Researchers still need to find out whether the medication could offer similar protection to women, particularly those at higher risk of breast cancer.
