Breastfeeding is associated with a 30% overall decreased risk of breast cancer recurrence among women who have previously had one subtype of the disease, according to a new study published in the Journal of the National Cancer Institute.

Share on Pinterest Breastfeeding may make the breasts less susceptible to carcinogens, leading to slower growing tumors.

The team behind the new study, from the Kaiser Permanente Division of Research in Oakland, CA, claims that this is the first study to examine the role of breastfeeding history in cancer recurrence.

The new study is part of ongoing research in breast cancer from the Kaiser Permanente team. Last year, the team discovered that patients with specific HER2+ breast cancer tumors have a low risk of cancer recurrence within 5 years of diagnosis. In 2013, they found that consuming high-fat dairy products following diagnosis of breast cancer increases likelihood of dying from the disease.

In the new study, the team found that breastfeeding appeared to improve outcomes of women diagnosed with the luminal A subtype of breast cancer.

Women with these cancers had a 30% decreased risk of breast cancer recurrence if they had a history of breastfeeding. Breastfeeding mothers were also found to be 28% less likely to die from luminal A breast cancer. The protection was found to be strongest for women who had a history of breastfeeding for 6 months or more.

However, no significant improved outcomes for women with other subtypes of breast cancer were associated with breastfeeding.