Babies who were breastfed for at least six months had a 19pc lower risk of going on to develop leukaemia in childhood than those who were breastfed for a shorter period or not at all, research found.
Scientists said they made the findings after reviewing 18 different studies, while a separate analysis of 15 studies found that ever being breastfed compared with never being breastfed was associated with an 11pc lower risk of childhood leukaemia.
The researchers, at the University of Haifa in Israel, suggested more should be done to educate women on the health benefits of breastfeeding, while there should also be efforts to make it easier for women to do it in public.
Leukaemia is the most common cancer in childhood, but little is known about its cause.
Breastfeeding is recommended by Britain's NHS as the healthiest option for feeding babies up to the age of six months.
The number of women who breastfeed in the UK is increasing, according to the Royal College of Paediatrics and Child Health (RCPCH), with 55pc now breastfeeding at six weeks and 34pc at six months, but younger mothers and those living in areas of higher deprivation are the least likely to breastfeed.
The study authors suggest several biological mechanisms of breast milk may explain their results, including that it contains many immunologically active components and anti-inflammatory defence mechanisms that influence the development of an infant's immune system.