OAKLAND, Calif., May 1 (UPI) -- A new study by researchers at Kaiser Permanente suggests breast cancer survivors are less likely to experience a recurrence of the disease if they breastfed one or more of their children.
The study, which followed 1,636 breast cancer patients, also found that breastfeeding offered extra protection from breast cancer tumors of specific genetic subtypes.
"This is the first study we're aware of that examined the role of breastfeeding history in cancer recurrence, and by tumor subtype," lead study author Marilyn L. Kwan, a research scientist with the Kaiser Permanente Division of Research, said in a press release.
As part of the study, participants filled out questionnaires about their health and breastfeeding history. Health outcomes were plotted and compared against their answers.
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Women who reported breastfeeding were more likely to survive the disease and less likely to experience a relapse or second bout. Most of the benefits were attributed to the fact that women who breastfeed are more likely to develop Luminal A tumors, which include some of the most common types of breast cancer tumors.
Luminal A tumors, and especially tumors of the subtype called estrogen-receptor positive, are less aggressive and easier to treat. They respond more positively to hormone therapy.
Researchers aren't sure why breastfeeding is correlated with the more treatable Luminal A tumors.
"Breastfeeding may increase the maturation of ductal cells in the breast, making them less susceptible to carcinogens or facilitate the excretion of carcinogens, and lead to slower-growing tumors," said study co-author Bette J. Caan, a senior research scientist with the Division of Research.
Breastfeeding is shown to have a range of short- and long-term benefits for the health of a child, and this latest study suggests there are benefits for the mom, as well. The research even showed that more breastfeeding was better than less breastfeeding.
"In fact, the protection was even stronger for women who had a history of breastfeeding for six months or more," Kwan added.
The new research was published in the Journal of the National Cancer Institute.
