Does High B12 Mean Cancer?

An elevated serum vitamin B12 level has been linked with an increased risk of advanced cancer stages. Carmel and Eisenberg first recognized this relationship between cancer patients with elevated B12 levels and shorter survival rates than those who had normal or lower levels of this vitamin in 1977, when several other studies confirmed their observations. The results of these studies vary considerably, however. One found no association between elevated B12 levels and mortality for patients with advanced cancer, while another associated their tumor presence with increased levels. A recent report in Critical Care Medicine also concluded that higher B12 levels may be more associated with hematologic malignancies rather than solid cancers.

However, recent findings that unexplained high B12 levels are linked to an elevated incidence of solid cancers suggest this may be an early biological marker that cannot easily be diagnosed or excluded through conventional methods. As such, the current study was undertaken to investigate this relationship further and whether its strength varied depending on levels of B12 elevation.

This study included all critically ill patients admitted to Angers University Hospital from January 2007 through May 2015 who underwent at least one B12 measurement with at least one value above 1000 pmol/L between January 2007 and May 2015. All measurements (T1-T2) had at least one value above this threshold within 1 to 48 months from their earliest reading (T1); the duration of an elevated B12 level was also determined, with analysis limited only to cases in which it either stabilized or increased over time.

We employed the statistical software R to conduct our analyses. Variables included patient sex, age, and date of B12 measurements, as well as information regarding incident cancers occurring within 60 months following T1 measurement; information such as primary cancer location or metastases were also collected.

An association was found between elevated B12 levels and solid cancers, such as those of the pancreas, esophagus/stomach, colon/rectum/kidneys/lungs, as well as lymphomas/myelodysplastic syndrome/multiple myeloma; weaker associations were observed.

This link between elevated B12 levels and cancer was unrelated to other known causes. It strengthened with increasing B12 elevation levels, with site and presence or absence of metastases being factors as well. No effect was seen from liver disease, which might increase B12 levels. Therefore, in our study, an unexplained high B12 level was an independent predictor of mortality for ICU patients once other risk factors had been taken into account. The high B12 group also displayed more severe illness as judged by MICU and CCU scores but not by CSRU scores, suggesting that high B12 levels are indicative of serious illness but may not accurately predict mortality among ICU patients when other composite measures of severity are considered.