A new study has found that women who breastfeed their babies have a significantly lower rate of breast cancer either recurring or killing them.

The study found that breastfeeding cut cancer recurrence chances by 30 percent, and the risk of dying from breast cancer dropped 28 percent, based on data from 1,636 women who had gotten breast cancer and then completed a questionnaire that focused on breastfeeding.

The study determined that breastfeeding protects the breast from certain types of tumor, particularly the hormone-sensitive strain, with lead researcher Dr. Marilyn Kwan from Kaiser Permanente saying that it’s the first study that looks at the role of cancer recurrence and tumor subtype when it comes to breastfeeding.

Additionally, the study determine that women who breastfeed typcially get the luminal A subtype of breast cancer if they get cancer at all, which is much less aggressive. Apparently, breastfeeding creates an environment where anti-oestrogen therapy is effective, according to the study.

Luminal A breast cancer is caused by the female hormone and is the most common form of the disease. It is less likely to spread to the rest of the body, making it more treatable with hormonal drugs.

However, scientists still need to answer the question of why it is that breastfeeding causes less-aggressive tumors. A co-author of the study suggested that breastfeeding may cause a maturation of ductal cells within the mass of breast tissue, which may make them less likely to be affected by carcinogens and cause tumors to grow more slowly.

The findings were published in the Journal of the National Cancer Institute.

Breast cancer is one of the most common forms of cancers, and it affects primarily women. Most health experts advise regular screenings via mammograms in order to catch the disease early, which dramatically increases the rate of survival from the disease.