Abstract
Background: Oral iron promotes intestinal tumourigenesis in animal models. In humans, expression of iron transport proteins are altered in colorectal cancer. This study examines whether the route of iron therapy alters iron transport and tumour growth. Methods: Colorectal adenocarcinoma patients with pre-operative iron deficiency anaemia received oral ferrous sulphate (n=15), or intravenous ferric carboxymaltose (n=15). Paired (normal and tumour tissues) samples were compared for expression of iron loading, iron transporters, proliferation, apoptosis, Wnt signalling pathway and microsatellite instability using immunohistochemistry and RT-PCR. Results: Iron loading was increased in tumour and distributed to the stroma in intravenous treatment and to the epithelium in oral treatment. The protein and mRNA expression of iron transporters were increased in tumours compared to normal tissues but there were no significant differences between the treatment groups. However, intravenous iron treatment reduced ferritin mRNA levels in tumours (p<0.001) and successfully replenished body iron stores without increasing tumour growth, DNA damage markers, proliferation or apoptosis compared with oral iron treatment. Conclusion: Iron distribution to non-epithelial cells in intravenous iron treatment suggests that iron is less bioavailable to tumour cells. Therefore, intravenous iron supplementation could be a safer option in the treatment of colorectal cancer patients with iron deficiency anaemia due to the differential compartmentalisation of iron within the intestinal mucosa and its efficiency in replenishing body iron levels without increasing the risk of tumour growth.Trial registration: The study was registered with the Medicines and Healthcare Regulatory Agency, clinical trials.gov (NCT01927328) and EudraCT (2013-000209-22).
Intravenous iron is non-inferior to oral iron regarding cell growth and iron metabolism in colorectal cancer associated with iron-deficiency anaemia
