Iron status in relation to cancer risk and mortality: Findings from a population-based prospective study

While experimental evidence suggests potential carcinogenic effects of increased iron load, there is a lack of data on iron status and cancer risk from epidemiological studies. Here, we evaluated prediagnostic serum concentrations of ferritin, iron and transferrin as well as transferrin saturation (TSAT) in relation to cancer risk and mortality in a prospective study by multivariable Cox regression analyses. A case-cohort sample of the population-based EPIC-Heidelberg Study including a random subcohort (n=2738) and incident cases of breast cancer (n=627), prostate cancer (n=554), lung cancer (n=195), colorectal cancer (n=256) and cancer death (n=759) was used. Ferritin levels were inversely associated with breast cancer risk in the multivariable Cox regression model, with a hazard ratio (HR) of 0.67 [95% confidence interval: 0.49, 0.92] for women in the highest quartile compared to those in the lowest quartile. Neither ferritin nor the other markers of iron status were significantly associated with colorectal, prostate or lung cancer risk. An inverse association was observed between ferritin and total cancer mortality (HR: 0.70 [0.53, 0.92]). There were no significant overall associations between serum iron, transferrin or TSAT and cancer mortality. The present findings do not support the notion of increased iron load constituting a cancer risk factor in the general population. By contrast, our analyses revealed inverse associations between ferritin levels and breast cancer risk as well as cancer mortality. What's new? While experimental evidence suggests carcinogenic effects of increased iron load, there is a lack of data on iron status and cancer risk from epidemiological studies. Here, the authors evaluated associations between prediagnostic serum levels of ferritin, serum iron, transferrin and transferrin saturation and the risk of common cancers using a large case-cohort sample. The established biomarkers of iron status were not associated with increased cancer risk. By contrast, higher serum ferritin was related to lower risks of breast cancer and cancer mortality. The findings suggest that higher iron load does not constitute a cancer risk factor in the general population.