text_1: Study Suggests Breastfeeding May Lower Risk of Childhood Leukemia
text_2: Do formula-fed children face increased risk of leukemia? This news release summarizes a published report on data from 18 separate studies worldwide that, when analyzed together, suggest breastfeeding is associated with reduced risk of developing childhood or adolescent leukemia. But that’s basically the only message conveyed by the news release, which is otherwise devoid of important context, including — most importantly — on the limitations of the observational design used by all of studies in the analysis. The release’s incomplete, one-sided presentation will most likely lead to a flurry of overblown media coverage that could have negative repercussions for the many women who cannot or choose not to breastfeed. There are many reasons for women to think that breastfeeding is a good choice for their babies. Is leukemia prevention one of them? That’s the suggestion of the study reported on here, which is a re-analysis of previous studies examining the question. It’s worthwhile research, but let’s remember that these underlying studies all relied on a backward-looking case-control design that is subject to selection bias and a variety of other potential problems. And the scope of the potential benefit for this condition, which is thankfully quite rare, is limited. Our worry here is that women face a number of physical and lifestyle constraints that may affect their ability to breastfeed. And women who can’t breastfeed already experience guilt that they aren’t doing enough for their babies. Should they also be made to feel as if they are putting their children at increased risk of cancer? That’s not a justifiable message based on this study. But without more careful communication of study limitations and other context, we’re afraid that that’s the message that could ultimately reach the public.