Breastfeeding After Breast Cancer Treatment Seems Safe

Women — including women with a BRCA mutation — who breastfeed after receiving breast cancer treatment don’t have a higher risk of recurrence (the cancer coming back) or a new breast cancer, according to two studies presented at the ESMO Congress 2024.

One study looked specifically at women with a BRCA1 or BRCA2 mutation, both of which increase the risk of developing breast cancer. The other study analyzed new information from the POSITIVE trial on breastfeeding in women diagnosed with hormone receptor-positive breast cancer who paused hormonal therapy to become pregnant.

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  The first study looked at women with a BRCA mutation who gave birth after breast cancer treatment. It found no difference in the number of breast cancer recurrences or new breast cancers between women who breastfed and women who didn’t. There was also no difference in survival.

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  In the POSITIVE trial, about 60% of women who had a child breastfed. Rates of a new breast cancer or breast cancer recurrence were the same in women who breastfed and women who didn’t: about 3%.

If you would like to have a child and breastfeed after breast cancer treatment, these two studies offer evidence that you can safely do that, even if you have a BRCA mutation.

“These results are key for women who wish to become pregnant and breastfeed their baby after breast cancer,” study co-author Fedro Alessandro Peccatori, MD, PhD, director of the fertility and procreation unit at the European Institute of Oncology, in Milan, Italy, said in a statement. “[W]ith this new information we can debunk the myth that breastfeeding is neither possible nor safe for breast cancer survivors. They can have a normal pregnancy and relationship with their baby, including breastfeeding.”

The study looking at breastfeeding in women with a BRCA mutation included nearly 5,000 women age 40 or younger who had received treatment for stage I to stage III breast cancer between 2000 and 2020.

The POSITIVE trial included 518 women who temporarily stopped hormonal therapy treatment for early-stage hormone receptor-positive breast cancer to try to get pregnant.

In the first study, of 4,732 women with a BRCA mutation, 474 women had a child. About 23% of the women who gave birth breastfed their babies. 

The researchers followed the women for about seven years after they gave birth.

There was no difference in the recurrence rates or the number of new breast cancers between women who breastfed and women who didn’t. There also was no difference in disease-free survival (how long the women lived without the cancer coming back) or overall survival (how long the women lived whether or not the cancer came back).

In the POSITIVE trial, 317 women had at least one child, and 62% of these women breastfed. Two years after the first woman in the study gave birth, 3.6% of the women who breastfed had a recurrence or were diagnosed with a new breast cancer compared to 3.1% of women who didn’t breastfeed.

Blondeaux E, et al. Breastfeeding after breast cancer in young BRCA carriers: results from an international cohort study. Abstract 1815O, ESMO Congress 2024.

Azim HA, et al. Breastfeeding in women with hormone receptor-positive breast cancer who conceived after temporary interruption of endocrine therapy: Results from the POSITIVE trial. Abstract 1814O, ESMO Congress 2024.