The protective effect of breastfeeding on breast cancer

“Breastfeeding can help control obesity in our children during their childhood and adulthood lives, but it also has a protective impact on breast cancer in breastfeeding mothers,” says PhD candidate Narges Alianmoghaddam.


Narges Alianmoghaddam, Registered Midwife and PhD candidate of Midwifery at the School of Public Health.

Public health researchers from Massey University’s College of Health are calling for more research into the possible protective effects of breastfeeding on the recurrence of breast cancer in those who have previously had the disease.

It comes as a result of a recently-published commentary, titled Breast Cancer, Breastfeeding and Mastectomy: A Call for More Research, in the world’s most cited breastfeeding journal, Journal of Human Lactation.

The paper, by Massey University PhD candidate Narges Alianmoghaddam and her doctoral supervisor Associate Professor Cheryl Benn along with colleagues Dr Kaveh Khoshnood and Professor Holly Powell Kennedy from Yale University, United States and Dr Minoor Lamyian from Tarbiat Modares University, Iran, highlights the lack of research relating to the potential protective effects of breastfeeding after breast cancer.

“Our paper draws attention to the high rate of mastectomy [the removal of the entire breast] among premenopausal women across the world. Removal of breasts eliminates the chance of future breastfeeding, an optimal method of infant feeding. Although we found several studies that show the possibility of breastfeeding in breast cancer survivors, especially in women who had breast conserving therapy [the removal of the tumour only, with treatment via radiation therapy] or unilateral mastectomy, we could not find any research on the protective effect of breastfeeding after breast cancer treatment regarding recurrence of breast cancer, or developing breast cancer in the second breast for breast cancer survivors. I would like to pursue this research further, and hope to do so in my post-doctorate studies,” Mrs Alianmoghaddam says.

How can breast feeding support better health?

She says the New Zealand population suffers from high rates of obesity and breast cancer, but breastfeeding could change that. “Breastfeeding can help control obesity in our children during their childhood and adulthood lives, but it also has a protective impact on breast cancer in breastfeeding mothers.

“Research shows, every 12 months of breastfeeding in a woman’s lifetime leads to a significant decline in the risk of developing invasive breast cancer significantly. Through promoting breastfeeding, the New Zealand health system could reduce rates of obesity and breast cancer to a certain extent.”

Breast cancer is the most common form of cancer affecting women worldwide. Recent research published in The Lancet by Professor Cesar Victora et al (University of Pelotas, Brazil), shows with the current rate of breastfeeding, about 20,000 breast cancer deaths are prevented globally, compared to if no women breastfed.

“There is a chance an additional 20,000 deaths caused by breast cancer could be prevented annually if the duration of breastfeeding increases to one year per child amongst women in high-income countries including New Zealand, or to two years per child in low and middle income countries,” Mrs Alianmoghaddam says.

“In New Zealand the rates of exclusive breastfeeding at six months continue to decline, while health professionals, especially midwives and lactation consultants, are actively involved in promoting and supporting six months exclusive breastfeeding.

“For example, in New Zealand in 2014, more than eight out of ten infants were exclusively breastfed at discharge from hospital, 42 per cent at three months and only 16 per cent at six months. This number is far below WHO’s health target of 50 per cent for six months exclusive breastfeeding rates.”

Health benefits

Despite widespread consensus regarding the health benefits of exclusive breastfeeding for mother and baby, prevalence is very low worldwide. According to the World Health Organisation in 2016, increased breastfeeding rates can avert 800,000 child deaths and provide savings of $300 billion (US) each year across the world. Consequently, promoting breastfeeding especially increasing the rate of exclusive breastfeeding at six months from the current rate of 38 per cent to at least 50 per cent by 2025 has become a global health target.

“The key conclusion of our paper is the importance of breast cancer awareness in reproductive age women. We should educate our girls and young women about the method of breast self-examination and about the early signs of breast cancer. We should educate mothers about the health benefits of breastfeeding for themselves, highlighting the protective effect of breastfeeding on the occurrence of breast cancer in breastfeeding mothers. All mothers should be encouraged and supported to breastfeed their children for a longer duration regardless of having a history of breast cancer,” Mrs Alianmoghaddam says.

“Patients under 40 years of age make up about 5 per cent of the overall breast cancer population in the United States. In New Zealand, in 2011, more than 11 per cent of breast cancer patients were aged 25 to 44. However, in developing countries, including Arab countries, that rises to half of the breast cancer patients being in the reproductive age range.

“For successful breast conserving therapy, breast cancer needs to be detected in the early stages, but detection in childbearing age women is challenging. Although mammography can save lives via diagnosing breast cancer about five years earlier than clinical examinations, it is less efficient in reproductive age women for several reasons including high rates of false negative results, breast density and over-diagnosis,” she says.

Mrs Alianmoghaddam is a Registered Midwife and PhD candidate of Midwifery at Massey’s School of Public Health. Her doctoral research is about promoting six months exclusive breastfeeding in New Zealand. Her doctoral supervisors are Dr Suzanne Phibbs, senior lecturer for the School of Public Health, and Associate Professor Cheryl Benn, a Registered Midwife an International Board Certified Lactation Consultant (IBCLC).

Massey University