- Women who had been breastfed during infancy were at increased risk for adulthood colorectal cancer, colorectal polyps, and appendicitis, suggesting possible long-term effects of infant feeding practices on the gastrointestinal tract.
Why this matters
- Breastfed infants are known to have many short-term benefits compared with bottle-fed infants in terms of lower risks for infection and obesity in infancy and childhood, and some evidence suggested reduced long-term risk for obesity and diabetes in adulthood.
- However, evidence on its long-term effect on the risk for adult cancers is limited.
- This large prospective study compared the incidence of 8 common cancers in 548,741 women without prior cancer who were (n=395,363) and were not breastfed during infancy (n=153,378).
- Funding: Medical Research Council and Cancer Research UK.
- During 9.8 million person-years (12.7 years per woman) of follow-up, 57,998 incident cancers were reported across 8 most common cancer sites.
- Women who had been breastfed vs not had a significantly higher risk for colorectal cancer (adjusted relative risk, 1.18; 95% CI, 1.12-1.24) but not for other 7 cancers.
- Compared with women who had not been breastfed, those who had been breastfed were more likely to have benign colorectal polyps (RR, 1.09; 95% CI, 1.05-1.13; P<.0000001 and appendicitis ci p=".0008)" but less likely to have inflammatory bowel disease>
- Risk of confounding.
- Results cannot be generalised to younger ages or extrapolated to lifetime cancer risks.