Breastfeeding May Benefit Moms, Too

Breast cancer recurrence may be reduced in mothers who breastfed their children

(RxWiki News) Breastfeeding may not just bring benefits to baby.

Breastfeeding might help protect moms who develop breast cancer, a new study from Kaiser Permanente found.

The authors of this study found that for some tumors, breastfeeding had a protective effect. Women who had breastfed their babies were less likely to have their cancer come back (recur) after treatment.

"We need more studies to confirm the findings," said Jame Abraham, MD, director of the Cleveland Clinic Breast Oncology Program, in an interview with dailyRx News. "If it is validated in other studies, this will have implications in patient care or lifestyle."

Women who had breastfed were also less likely to die from breast cancer. The reason behind this apparent effect was unclear.

"This is the first study we're aware of that examined the role of breastfeeding history in cancer recurrence, and by tumor subtype," said lead study author Marilyn L. Kwan, PhD, a researcher with Kaiser Permanente's Division of Research, in a press release.

Breast cancer is not a single disease but occurs in multiple forms known as subtypes. Subtypes differ in terms of risk factors and aggressiveness. They may also respond to different treatments. Survival rates may also vary by subtype.

Researchers think that breastfeeding might protect women from cancer because it may decrease the total number of menstrual periods they have. Fewer periods may mean lower exposure to sex hormones that affect the menstrual cycle.

Dr. Kwan and colleagues studied data from surveys and medical records of more than 1,600 women with breast cancer.

Breastfeeding appeared most protective for women who had the luminal A breast cancer subtype. Luminal A is the most commonly diagnosed breast cancer subtype.

Dr. Kwan and colleagues found that if women who breastfed their kids did develop cancer, it was more likely to be the luminal A form. This may be beneficial to those women, because luminal A is less aggressive and more responsive to treatment than other subtypes.

"So we have a tumor that is slow growing, and we have an effective treatment," Dr. Abraham said. "That will lead to decreased recurrence and improved survival."

Dr. Abraham added, "Those cancer cells slowly divide and, in general, have a [less painful] course. Luminal A type of breast cancer is more responsive to anti-estrogen therapy."

Breastfeeding may also decrease the risk of the disease recurring after treatment by 30 percent, Dr. Kwan and team found. Women who breastfed were also 28 percent less likely to die from breast cancer.

"Women who breastfeed are more likely to get the luminal A subtype of breast cancer, which is less aggressive, and breastfeeding may set up a molecular environment that makes the tumor more responsive to anti-estrogen therapy," Dr. Kwan said. "In fact, the protection was even stronger for women who had a history of breastfeeding for 6 months or more."

This study was published April 28 in the Journal of the National Cancer Institute.

The National Institutes of Health and the Huntsman Cancer Institute funded this research.

Study author Philip S. Bernard had financial interest in Bioclassifier LLC and University Genomics. Bioclassifier provides genetic testing for cancer.

Review Date: 
April 28, 2015