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Nearly every newborn in the USA is given the Vitamin K injection at birth or within a few days after. The shot is meant to help the infants quickly build the biochemical pathways that allow for quick blood clotting, because hemorrhage, in the brain and other areas, does happen sometimes from the birthing process.

However, there are conflicting reports that the shot has been linked to Cancer and, specifically, Leukemia.

Midwifery Digest, Vol 2 #3, September 1992 estimated that the chance of your child developing leukemia from the vitamin K shot is about one in 500! This means that the risk of developing leukemia from the vitamin K shot is much higher than the risk of bleeding on the brain which the vitamin K shot is supposed to prevent!
Source

I would think the 1 in 500 stat would mean more if I knew the prevalence of leukemia in children who did not receive the shot.

Another source says that there is absolutely no connection, but it is still in favor of avoiding the treatment, just as the first source is.

It was suggested some years ago that vitamin K injections were associated with cancer and leukemia. However, that conclusion was in error. There is NO known association between the two.

As mentioned above, these injections are absolutely inappropriate for your baby -- but the increased risk for cancer is not a legitimate concern.
Source

As it sits with me right now, I trust Dr. Mercola more than Sarah the health blogger, but that is because I am familiar with some of Dr. Mercola's other work and found it reasonable. The issue is that Sarah seems to quote a source more reputable than her, but it is from 1992.

So is there a connection between the newborn vitamin K injection and cancer or leukemia? Are there any actual studies on this topic that allow us to reject or accept this hypothesis?

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    "I am familiar with some of Dr. Mercola's other work and found it reasonable." You might like to have a look at the joseph-mercola tag and see if you still take this view. – Oddthinking Dec 30 '13 at 5:08
  • FYI: A more exact reference for the first claim is Sally Yarnley. MIDIRS Midwifery Digest, Sep 1992, 2:3, p363, but I still haven't been able to track down the original research paper. – user5582 Dec 30 '13 at 6:19
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    @Oddthinking Every question with that tag only mentions him in passing. The answers on almost all of those questions are not very definitive, usually ending with "there needs more study." One post thought it prudent to call him a quack and says he is "at is again"; not very unbiased for a community that claims to be. – fredsbend Dec 30 '13 at 7:36
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I can't find the text of the original 1992 Midwifery Digest article, however, there is more recent work addressing the same question. It is scientifically dishonest for somebody to cherry-pick that 1992 study and not mention the research that has been done since then.

(Klebanoff et al. 1993) noted that "two recent studies have found that infants who received intramuscular vitamin K were at twice the expected risk for cancer during childhood." They referenced (Golding et al. 1990) and (Golding et al. 1992). All the work since then refers back to Golding et al. as having suggested the association between vitamin K and leukemia. My guess is that it is Golding et al. that was mentioned in the Midwifery Digest as they estimated the incidence between 1.87 and 2.04 per 1000 (matching approximately the 1 per 500 in the claim). (Klebanoff et al. 1993) performed an independent study to examine this hypothesis.

They found "no increased risk of either cancer in general or leukemia in particular among children who received vitamin K during the perinatal period; this finding is in accordance with the observation that the incidence of childhood leukemia in the United States did not increase from 1948 (when few or no newborns received vitamin K) to 1980 (when nearly every newborn received the drug)."

(Vitamin K Ad Hoc Task Force 2003) also addressed the evidence behind this hypothesis. They summarized:

The Vitamin K Ad Hoc Task Force of the American Academy of Pediatrics reviewed the reports of Golding et al and other information regarding the US experience and concluded that there was no association between the intramuscular administration of vitamin K and childhood leukemia or other cancers.

Additional studies that have since been conducted by other investigators have not supported a clinical relationship between newborn parenteral administration of vitamin K and childhood cancer.

They mention specifically (Ross and Davis 2000) that "found no randomized or quasi-randomized evidence of an association between parenteral vitamin K prophylaxis and cancer in childhood. Ten case-control studies were identified, of which 7 found no relationship and 3 found only a weak relationship of neonatal administration of intramuscular or intravenous vitamin K with the risk of solid childhood tumors or leukemia."

The Vitamin K Ad Hoc Task Force also notes that "recent research on the pathogenesis of childhood leukemia additionally weakens the plausibility of a causal relationship between parenteral administration of vitamin K and cancer."

Last, the Cochrane Review of (Puckett and Offringa 2000) stated that "taken as a whole, these studies do not establish a causal relationship between these routes of administration and an increased risk of cancer", and that "no randomized or quasi randomized evidence with regard to the association between parenteral vitamin K prophylaxis and cancer in childhood was found."

Why might the original studies have found an association?

Maybe there was a correlation in the Golding et al. sample that doesn't exist in the full population. There is always a small risk of a false positive. However, a few things stand out to me that might have increased the risk of a false positive in those initial studies.

The original studies (and even many of the subsequent studies) were case-control studies. One draw-back of this type of study "relates to the difficulty of obtaining reliable information about an individual’s exposure status". This was evident in the studies of Golding et al. They admit that "one of the problems encountered in abstracting data from the notes was the fact that the route of vitamin K administration was often not recorded, although vitamin K was noted as having been given." They employed "several strategies [...] to identify the probable route of administration". These were not blinded.

Contrast that with the study of Klebanoff et al., which, while also a (nested) case-control study, used data from a previous prospective cohort study, that had exact records of a child's vitamin K administration (route, dose, name, for example). The later cancer diagnoses were blinded as to the vitamin K exposure status.

Additionally, Golding et al. tested for multiple correlations (at least two: pethidine, and Vitamin K), and reported significance without correcting for multiple hypothesis tests. Test for enough correlations, and you'll find one by chance.

References

Golding, J., M. Paterson, and L. J. Kinlen. "Factors associated with childhood cancer in a national cohort study." British journal of cancer 62, no. 2 (1990): 304.

Golding, Jean, Rosemary Greenwood, Karen Birmingham, and Martin Mott. "Childhood cancer, intramuscular vitamin K, and pethidine given during labour." BMJ: British Medical Journal 305, no. 6849 (1992): 341.

Klebanoff, Mark A., Jennifer S. Read, James L. Mills, and Patricia H. Shiono. "The risk of childhood cancer after neonatal exposure to vitamin K." New England Journal of Medicine 329, no. 13 (1993): 905-908.

Puckett, R. M., and M. Offringa. "Prophylactic vitamin K for vitamin K deficiency bleeding in neonates." Cochrane Database Syst Rev 4 (2000).

Ross, Julie A., and Stella M. Davies. "Vitamin K prophylaxis and childhood cancer." Medical and pediatric oncology 34, no. 6 (2000): 434-437.

Vitamin K Ad Hoc Task Force. "Controversies concerning vitamin K and the newborn." Pediatrics 112, no. 1 (2003): 191-192.

  • Very nice research. I had a feeling that there had been more study since 1992. Regarding the pathways of Vitamin K and the pathogenesis of leukemia being incompatible and unrelated, that may be true, but the question is about the shot, not vitamin K, which undoubtedly has other ingredients, such as preservatives, which may be the harming factor, if there is one. But, as the research seems to show, probably no correlation. – fredsbend Dec 30 '13 at 7:49
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    @fredsbend Thank you. Just to clarify, that sentence mentions not just vitamin K, but "administration of vitamin K". It's clearer in context. The task force mentions the discovery of an acute lymphocytic leukemia-associated gene, and that "a genetic etiologic explanation further lessens the likelihood of a clinically significant relationship between intramuscular administration of vitamin K and leukemia." – user5582 Dec 30 '13 at 7:55

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