The effectiveness of intravenous iron for iron deficiency anemia in gastrointestinal cancer patients: a retrospective study.

Background: Knowledge of the role of intravenous iron without the use of additional erythropoietic stimulating agents in anemic cancer patients is limited. This study evaluated the effect of ferric carboxymaltose (FCM) in a group of digestive oncology (DIO) patients and aimed to differentiate therapy response according to different types of iron deficiency (ID) anemia.

Methods: In this retrospective study, we identified DIO patients who were receiving FCM and had eligible baseline and follow-up hemoglobin (Hb) levels that did not require red blood cell transfusion. Subgroup analyses examined adequately versus inadequately treated patients and low (<100 µg/L) vs. high (>100 µg/L) baseline ferritin levels. Inadequate treatment was defined as administration of an insufficient dose of FCM, based on the modified Ganzoni formula.

Results: A total of 414 patients were receiving FCM, of whom 41 were excluded because of transfusion and another 70 because of unknown or inadequate baseline iron status. Thus, the study group consisted of 303 patients. Follow-up serum levels were evaluated after a median of 4 weeks. Overall, the median change between baseline and follow-up Hb was 0.5 (interquartile range [IQR]: -0.1-1.6) g/dL. No significant difference in this change was found between the adequately and inadequately dosed groups. The median change in Hb was significantly greater in the low baseline ferritin group than in the high baseline ferritin group: 1.2 (IQR: 0.3-2.2) vs. 0.4 (IQR: -0.3-1.4) g/dL, respectively; P=0.004.

Conclusions: Intravenous administration of iron in DIO patients with ID anemia leads to a significant increase in Hb. Moreover, differentiating between the types of ID anemia based on ferritin levels could be applied to predict therapy response, although better biomarkers are needed.