Breastfeeding is associated with a lower risk of developing an aggressive form of breast cancer known as hormone-receptor negative, according to a large international scientific study.
This new combined evidence shows the risk of developing this form of breast cancer – which usually shows up in women under the age of 50 – reduced by up to 20 per cent in women who breastfed.
Hormone-receptor-negative (HRN) breast cancers are more likely to be aggressive and life-threatening. Women with the BRCA1 gene mutation – the mutation brought to public consciousness by actress Angelina Jolie, who had her breasts removed because she had the gene – are more likely to develop HRN cancers.
HRN breast cancers represent about 20% of all breast cancers. This subtype of breast cancer has no receptors for the hormones oestrogen or progesterone; about two-thirds of these HRN cancers also have no receptors for HER2 (human epidermal growth factor receptor 2). Breast cancers with no receptors for oestrogen, progesterone, or HER2 are called triple negative (TN).
HRN and TN breast cancer are more often deadly because they tend to be diagnosed at later stages, respond to fewer treatment options, and are less likely to be cured by current therapies.
“Further evidence to support the long-term protection of breastfeeding against the most aggressive subtypes of breast cancer is very encouraging and actionable,” says Dr Marisa Weiss, president and founder of one of the study’s lead collaborators, Breastcancer.org.
“Breastfeeding is a relatively accessible, low-cost, short-term strategy that yields long-lasting natural protection.”
“This work highlights the need for more public health strategies that directly inform women and girls about the maternal (and foetal) benefits of breastfeeding before and during a woman’s child-bearing years. It’s also important for these women to have the message reinforced by their healthcare professionals.”
The study, known as a meta-data analysis, and published in the scientific journal Annals of Oncology, reviews hundreds of peer-reviewed and published research papers from around the world to establish over-arching trends in international research.
The study’s findings follow research published in April which found that women diagnosed with breast cancer who previously breastfed their babies had a 30 percent overall decreased risk of the disease recurring.
“Pregnant women and young mothers are highly receptive and motivated to make healthy choices. We need to encourage women who are able to breastfeed to do so for their breast health, in addition to the health of their children,” says Dr Paolo Boffetta, associate director for population sciences Mount Sinai Hospital in Manhattan.
“Further prospective research will be necessary to further understand the full impact of breastfeeding duration and its effect on other subtypes.”
