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Anemia in Cancer Patients: Significance, Epidemiology, and Current Therapy

Anemia in Cancer Patients: Significance, Epidemiology, and Current Therapy

ABSTRACT: Anemia in cancer patients is associated with a decline in energy levels, activity levels, and quality of life, and these variables improve when hemoglobin levels rise. Importantly, the impact of improved hemoglobin levels on response to chemotherapy, radiation therapy, and survival time is under study. This line of research follows favorable preliminary data in clinical studies suggesting improved treatment outcomes with reversal of anemia. It is estimated that there are 10 million people in the United States with cancer. Of the 1.3 million cancer patients who are anemic with hemoglobin levels less than 12 g/dL, about 800,000 are receiving chemotherapy and 500,000 are not. The predominant treatable cause of anemia in these patients is a relative lack of erythropoietin; overall, only 20% of anemic cancer patients receive a trial of erythropoietic therapy. About one-fourth (26%) of patients whose hemoglobin is less than 12 g/dL and who are receiving chemotherapy for cancer are currently receiving erythropoietic therapy. A review of the patients in our oncology practice revealed that 37% were anemic (hemoglobin < 12 g/dL) prior to chemotherapy, and an additional 41% became anemic during chemotherapy. Overall, 63% of our cancer patients on chemotherapy received erythropoietin; 6% of these patients received red cell transfusions. Only 7% of our patients had a hemoglobin level < 10 g/dL before chemotherapy; overall, 80% of our patients maintained hemoglobin levels ³ 10 g/dL at all times. Barriers to the use of erythropoietic agents include cost and reimbursement issues, inconvenience of frequent injections, limitations in efficacy, and indication restrictions. An understanding of the importance of anemia and newer agents requiring less frequent dosing, such as darbepoetin alfa (Aranesp), may help physicians and patients overcome some of these barriers. [ONCOLOGY 16(Suppl 10):17-24, 2002]

Anemia is an important aspect
of cancer care because it is common, associated with symptoms such as poor quality
of life and declining physical function, and treatable.[1-5] Fatigue, a prevalent
problem in oncology patients, is also linked to anemia and is a key component
of physical function (Figure 1).[6-8]
Furthermore, recent research has revealed potentially important implications
of anemia as a variable that has impact on the efficacy of cancer therapies
including radiation therapy,[9,10] chemotherapy,[11] and combined- modality
treatment.[12-14] While research is ongoing, it is assumed that variations in
tissue oxygenation are probably responsible, at least in part, for these findings.

Anemia in Cancer Patients

The malignancy itself, or chemotherapy or other therapies can
cause decreased erythropoietin production or a reduced responsiveness in the
bone marrow to erythropoietin.[15] The presence of an invasive malignant process
triggers an immune response with the release of various cytokines that, in turn,
interfere with bone marrow function and shorten red cell survival. These are
probably the most common causes of cancer-related anemia. Other causes include
iron and vitamin B-12 deficiencies; additional vitamin and nutritional
deficiencies; bleeding; bone marrow metastases; various types of hemolysis;
infection; renal diseases; inflammatory disorders; a variety of hematologic diseases, including hemoglobinopathies; and endocrinopathies.

During the 1960s and 1970s, blood product transfusion support
was a mainstay of therapy encouraged by the advances in transfusion medicine. In
the last 20 years, increased recognition of the potential for transmission of
viral infections, as well as a limited blood supply, brought the need for
transfusion alternatives into the forefront.

Current Therapeutic Approaches

The advent of erythropoietic therapy over the past 10 years
has allowed physicians to reduce the need for transfusions. The recognition that
anemia treatment can improve the quality of life for patients has revolutionized
the field of oncology practice.

Other than red cell transfusions and/or erythropoietin
administration, specific therapies for anemia are only helpful in a few cases.
One such new and interesting therapy is the use of the CD20 monoclonal antibody
rituximab (Rituxan) in the treatment of autoimmune hemolytic anemias, pure red
cell aplasias, and cold agglutinin disease.[16-25] Iron replacement, vitamin
B-12 replacement, and the identification of occult (usually gastrointestinal)
bleeding are also important in some patients.

National Statistics:
Cancer and Anemia

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