Study finds iron levels not predictive of survival for form of blood cancer
Iron chelating drugs have been heavily promoted for use in patients with primary myelofibrosis (PMF), a form of blood cancer often treated with blood transfusion. These drugs, however, which withhold available iron in the body, are highly expensive and potentially toxic. A new study published in American Journal of Hematology finds that their increased use has been propagated by non-evidence based, and often industry-sponsored, statements and opinions, rather than original research, and that the conclusions are often based on poor data.
The study shows that the degree of anemia in patients suffering from PMF, age and need for red blood cell transfusion at diagnosis were stronger predictors for patient survival than serum ferritin level (a protein that stores iron), which is often used as a proxy for iron overload in the blood.
"Although iron chelation therapy in PMF would probably lower serum ferritin level in such patients, its value in terms of meaningful health outcomes remains dubious," says Dr. Ayalew Tefferi of the Mayo Clinic, principle author of the study.
In a related editorial in the journal, Dr. Thomas G. DeLoughery of Oregon Health & Science University states that "hematologists are under increasing pressure to prescribe iron chelation for seemingly any patient being transfused. However, there is no evidence that iron overload affects survival or morbidity."
The findings should impact clinical practice by discouraging the indiscriminate use of an expensive, potentially toxic and unproven therapy. The future challenge in treating myelofibrosis is to avoid transfusions by better therapies to reverse the stem cell defect. "Unfortunately, the recent focus on iron overload as a priority and not the stem cell defect is leading to a misallocation of resources on both the patient and practitioner's part," says DeLoughery.
