Cancer risk in women who were breastfed as infants

  • Yang TO & al.
  • Eur J Epidemiol
  • 11 Jun 2019

  • curated by Sarfaroj Khan
  • UK Clinical Digest
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Takeaway

  • 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.

Study design

  • 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.

Key results

  • 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>

Limitations

  • Risk of confounding.
  • Results cannot be generalised to younger ages or extrapolated to lifetime cancer risks.