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Breastfeeding, Pregnancy Seem to Improve Breast Cancer Survival

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We know that breastfeeding can lower breast cancer risk, especially if you breastfeed for longer than 1 year. This is because:

  • making milk limits breast cells’ ability to act abnormally
  • most women have fewer menstrual cycles when they’re breastfeeding, which means lower estrogen levels
  • many women tend to eat more nutritious food and make healthier lifestyle choices (avoiding alcohol and not smoking) while they’re breastfeeding

A small Swedish study suggests more benefits for breastfeeding: Women diagnosed with breast cancer who gave birth and breastfed for longer than 6 months had better breast cancer survival compared to women who didn’t give birth or breastfed for shorter periods of time.

The study was published in the July/August issue of Breastfeeding Medicine. Read “Breastfeeding Associated with Reduced Mortality in Women with Breast Cancer.”

In the study, the researchers followed up with a group of 630 women aged 25 to 74 who were diagnosed with and treated for breast cancer from 1988 to 1992 in the counties of Kalmar and Ostergotland, Sweden.

When the researchers started the study in 2004, 275 women had died, whether from breast cancer or other causes, and 10 women were in hospice care.

The researchers sent a questionnaire to the other 345 women asking about their pregnancy and breastfeeding history, including the number of children they had given birth to and how long they breastfed. A total of 250 women responded.

Sweden has nationalized health insurance. So the researchers tried to check the records of the 380 women that didn’t complete the questionnaire and figure out how many children each woman had and how long each child was breastfed. They were able to find the records of 91 women.

So overall, 341 women were included in the final analysis for the study:

  • 205 were still alive
  • 136 had died from breast cancer or another cause

Of the 341 women in the final analysis, 265 women had given birth.

Of the 265 women with children, the length of time spent breastfeeding was shorter among women who had subsequently died compared to women who were still alive.

The length of time the women breastfed and the number of pregnancies the women had were both linked to better breast cancer survival.

The researchers found that women diagnosed with breast cancer who breastfed for longer than 6 months and/or had at least one pregnancy had better survival than women who breastfed for shorter periods of time or had no pregnancies.

If breastfeeding is an option for you, you may want to consider it. Besides possibly lowering your breast cancer risk and your risk of recurrence and improving survival if you are ever diagnosed, breastfeeding gives your child antibodies through the breast milk that can protect her/him from bacterial and viral infections. Still, these are highly individual decisions affected by many factors besides breast cancer and recurrence risk and whether you are able to breastfeed.

Breastfeeding can be a challenge after a breast cancer diagnosis. After a double mastectomy, sadly, breastfeeding is impossible. After lumpectomy and radiation, the treated breast usually produces little or no milk, but the other breast usually can make milk normally. The milk from one breast may be enough or you may have to supplement with formula. Some women may choose to use a breast milk donor. An experienced breastfeeding coach can help you figure out the best possible solution for your unique situation.

Still, choosing to breastfeed is an extremely personal decision. For some women, it may be more practical to bottlefeed.

For more information on the benefits of breastfeeding, visit the Breastfeeding History page in the Lower Your Risk section.

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