Iron overload in myelodysplastic syndromes (MDS)

Within the myelodysplastic syndrome (MDS) work package of the European LeukemiaNet, an Expert Panel was selected according to the framework elements of the National Institutes of Health Consensus Development Program. A systematic review of the literature was performed that included indexed original papers, indexed reviews and educational papers, and abstracts of conference proceedings. Guidelines were developed on the basis of a list of patient- and therapy-oriented questions, and recommendations were formulated and ranked according to the supporting level of evidence. MDSs should be classified according to the 2008 World Health Organization criteria. An accurate risk assessment requires the evaluation of not only disease-related factors but also of those related to extrahematologic comorbidity. The assessment of individual risk enables the identification of fit patients with a poor prognosis who are candidates for up-front intensive treatments, primarily allogeneic stem cell transplantation. A high proportion of MDS patients are not eligible for potentially curative treatment because of advanced age and/or clinically relevant comorbidities and poor performance status. In these patients, the therapeutic intervention is aimed at preventing cytopenia-related morbidity and preserving quality of life. A number of new agents are being developed for which the available evidence is not sufficient to recommend routine use. The inclusion of patients into prospective clinical trials is strongly recommended.

Anemia is an established negative prognostic factor in myelodysplastic syndromes but the relationship between its degree and clinical outcome is poorly defined. We, therefore, studied the relationship between severity of anemia and outcome in myelodysplastic syndrome patients. We studied 840 consecutive patients diagnosed with myelodysplastic syndromes at the Fondazione IRCCS Policlinico San Matteo, Pavia, Italy, and 504 patients seen at the Heinrich-Heine-University Hospital, Düsseldorf, Germany. Hemoglobin levels were monitored longitudinally and analyzed by means of time-dependent Cox's proportional hazards regression models. Hemoglobin levels lower than 9 g/dL in males (HR 5.56, P=0.018) and 8 g/dL in females (HR=5.35, P=0.026) were independently related to reduced overall survival, higher risk of non-leukemic death and cardiac death (P<0.001). Severe anemia, defined as hemoglobin below these thresholds, was found to be as effective as transfusion-dependency in the prognostic assessment. After integrating this definition of severe anemia into the WHO classification-based Prognostic Scoring System, time-dependent regression and landmark analyses showed that the refined model was able to identify risk groups with different survivals at any time during follow up. Accounting for severity of anemia through the WHO classification-based Prognostic Scoring System provides an objective criterion for prognostic assessment and implementation of risk-adapted treatment strategies in myelodysplastic syndrome patients.

Iron accumulates in human atherosclerotic lesions but whether it is a cause or simply a downstream consequence of the atheroma formation has been an open question for decades. According to the so called “iron hypothesis,” iron is believed to be detrimental for the cardiovascular system, thus promoting atherosclerosis development and progression. Iron, in its catalytically active form, can participate in the generation of reactive oxygen species and induce lipid-peroxidation, triggering endothelial activation, smooth muscle cell proliferation and macrophage activation; all of these processes are considered to be proatherogenic. On the other hand, the observation that hemochromatotic patients, affected by life-long iron overload, do not show any increased incidence of atherosclerosis is perceived as the most convincing evidence against the “iron hypothesis.” Epidemiological studies and data from animal models provided conflicting evidences about the role of iron in atherogenesis. Therefore, more careful studies are needed in which issues like the source and the compartmentalization of iron will be addressed. This review article summarizes what we have learnt about iron and atherosclerosis from epidemiological studies, animal models and cellular systems and highlights the rather contributory than innocent role of iron in atherogenesis.