Lactation (breastfeeding) and cancer risk

Lactation (breastfeeding)We analyse global research on how lactation or breastfeeding affects the risk of developing cancer.


There is strong evidence that:

  • breastfeeding DECREASES the risk of breast cancer in the mother

The evidence shows that, in general, the greater the number of months that women continue breastfeeding their babies, the greater the protection these women have against breast cancer.

– This is the opinion of the Expert Panel and forms the basis of our Recommendation on breastfeeding

There is also other evidence that is limited (either in amount or by methodological flaws) but is suggestive of a decreased risk of ovarian cancer in women who breastfeed. Further research is required, and the Panel has not used this evidence to make recommendations.

Our Cancer Prevention Recommendation

> The advice for mothers is to breastfeed your baby, if you can.

A 2016 review of breastfeeding patterns around the world suggests that most mothers, regardless of income group, breastfeed their babies at some point after birth.

However, even in low-income countries, where breastfeeding rates tend to be higher than in high-income countries, only 47% of infants are exclusively breastfed for the first six months of life. The global average is 36%.

In our 2018 Third Expert Report, the term ‘lactation’ refers to the process by which the mother produces milk to breastfeed, whether directly or through expressing or pumping breastmilk. All the evidence about cancer risk presented in this part of the Third Expert Report relates to effects on the mother who is breastfeeding and not to effects on the child who is being breastfed.


Breastmilk provides a complete source of nourishment for newborns and young infants. The World Health Organization (WHO) recommends that babies should be exclusively breastfed (receive only breastmilk) for the first 6 months of life for the health of both mother and child, and that breastfeeding should continue for up to 2 years or beyond, alongside other appropriate foods and drinks.

Mechanisms: the biology linking lactation with cancer

> Read more about the cancer process

Emerging research

We fund research on how diet affects cancer risk through our regular grant programme. Read about the latest findings and ongoing projects here.

Diet and Cancer Report 2018

In 2018, we produced the Diet and Cancer Report, the third in our series of major reports looking at the many ways in which our diets, and how active we are, affect our cancer risk. You can find out much more about lactation and the risk of cancer by downloading a pdf of the relevant chapter in the 2018 report. Please note, however, that this webpage may have been updated since the report was published.