Cancers in Australia in 2010 attributable to total breastfeeding durations of 12 months or less by parous women

OBJECTIVES To estimate the proportion and number of cancers occurring in Australia in 2010 attributable to parous women having breastfed for total durations of ≤12 months. METHODS We estimated the population attributable fraction (PAF) of breast cancers (the only cancer site with convincing evidence of causal association) associated with women breastfeeding for ≤12 months in total, using standard formulae incorporating breastfeeding prevalence data, relative risks associated with breastfeeding and cancer incidence. We also estimated the proportion change in disease incidence (potential impact fraction [PIF]) that might have occurred under two hypothetical scenarios of women breastfeeding for longer durations. RESULTS An estimated 235 (1.7%) breast cancer cases that occurred in Australian in 2010 could be attributed to women breastfeeding for total durations of ≤12 months. Assuming a hypothetical increase in breastfeeding, we estimated that the number of breast cancers prevented would range from 36 to 51 (prevented fraction = 0.3% to 0.4%). CONCLUSIONS More than 200 breast cancers were attributable to women breastfeeding for total durations of ≤12 months. IMPLICATIONS Policies to increase breastfeeding duration may help prevent breast cancers in the future.