A new study says breastfeeding can reduce a mother's risk of developing an aggressive type of cancer called hormone-receptor negative. The findings showed that the risk decreased by as much as 20 percent in women who breastfed.
Breastfeeding is associated differently in each subtype of breast cancer. The intensity is defined by the receptor status, each type reflecting unique mechanisms of carcinogenesis. Hormone-receptor-negative (HRN) breast cancers are said to be highly aggressive. This type commonly affects women nearing the age of 50. Obesity and multiple early pregnancies are two of the external factors which can augment the chances of a woman to develop this type of breast cancer.
Women with multiple risk factors are thought to be least likely to breastfeed, say the researchers who conducted the breastfeeding meta-analysis. With that hypothesis, researchers from different institutions conducted a systematic review of case-control and prospective cohort studies to investigate the link between breastfeeding and breast cancer. The association was assessed through estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) status.
The meta-analysis represents 36,881 breast cancer cases in 27 studies, eight of which were cohort and 19 were case-control. The risk was determined by measuring the association of women who breastfeed with the breast cancer receptors (ER, PR, and HER2) and comparing it with those of women who don't.
Given the findings, it showed that women who breastfed had a significantly stronger inverse association with triple-negative breast cancers than women who never breastfed. Breastfeeding has a protective effect against hormone receptor-negative breast cancers, especially in younger women.
"Further evidence support the long-term protection of breastfeeding against the most aggressive subtypes of breast cancer is very encouraging and actionable," says Marisa Weiss, M.D, president and founder of Breastcancer.org, in a press release. "Breastfeeding is a relatively accessible, low-cost, short-term strategy that yields long-lasting natural protection."
With this meta-analysis, it is critical to remove the barriers to breastfeeding in lactating mothers. "All approaches will be necessary in order to protect the most women against the devastation of breast cancer over their lifetimes," adds Farhad Islami, M.D., Ph.D., director of interventions, American Cancer Society.
The study appears in the journal Annals of Oncology.