A Link Between In Vitro Fertilization and Childhood Cancer: Does It Matter?


Welcome to Impact Factor, I’m Perry Wilson. In vitro fertilization is a stressful process
for potential parents, with costs measured in emotional turmoil, medication side effects,
and thousands or tens-of-thousands of dollars. Against that backdrop, a new study appearing
in JAMA Pediatrics adds to the stress by linking the procedure to a small, but significantly
increased risk of childhood cancer. This is the first US study to really tackle
this issue. Researchers undertook the herculean task of
linking the Society of Assisted Reproductive Technology and Clinical Outcomes database
(which contains about 90% of all IVF treatments in the US) to state-level birth and cancer
registries. In the end, that added up to 275,686 kids
conceived via IVF. Over around four-and-a-half years of follow-up,
321 of those kids developed cancer. That’s 1 out of 858 kids. That’s a small number, though not as small
as any of us would like. The researchers used similar methods to identify
2.2 million kids born without IVF. In that group, the rate of cancer was one
in 1100 kids. That difference – 1 out of 858 versus 1
out of 1100 just made our standard cutoff for statistical significance. The authors zeroed in on hepatoblastoma and
embryonal cell cancers as potentially driving the overall association. Now of course there are many factors that
differed between the kids conceived via IVF and those that weren’t. Their moms were substantially older, more
educated and more likely to be white. The researchers adjusted for these factors
but point out that there is no real way to tell whether the increased cancer risk is
due to something about IVF or related to the underlying infertility problem in the first
place. But let’s do a thought experiment – what
if it is due to IVF. Does it matter? Studies like this face an implicit problem
of interpretation because using IVF versus not using IVF is not really a choice like
choosing drug A over drug B is. Like, for couples who are worried about childhood
cancer, what are we saying – just don’t have a kid at all? Put it this way – using the data in this
study I can calculate that to prevent one cancer in a kid under 10, you’d have to
stop 3400 successful IVF treatments. I feel like that’s throwing out the baby
with the bathwater. Maybe the results mean we need to be more
vigilant about kids who are conceived by IVF? The authors state as much in their conclusion
saying “These results suggest that continued follow-up of children conceived via IVF for
cancer occurrence is warranted”. But… should we? Probably not. Frankly, I’m not even sure what kind of
continued follow-up is being implied here. Routine screening CT scans for hepatoblastoma? The risk of such a strategy in terms of stress,
false-positives, and of course costs would seem to me to really outweigh the benefits. No, studies like this can really only be said
to be a first step in finding some pathway that will teach us more about childhood cancers
– and that’s what interests me. What can the biology of infertility and IVF
teach us about cancer in general, so we can reduce the risk of childhood cancer for everyone?

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