Anemia in cancer patients arises from both the cancer itself and from chemotherapy. Moreover, the prevalence of anemia is nearly twice as high in patients with hematological malignancies.1 Close to 40% of solid tumor patients have anemia, and its frequency increases as the duration of chemotherapy increases.1
The risk for anemia is even higher for patients with a low initial hemoglobin level (≤12.9 g/dL in females and ≤13.4 g/dL in males), female patients, those with lung or gynecologic cancers (compared to gastrointestinal [GI] or colorectal cancers), and in patients with cancer at any site, other than GI or colon/rectum, who have been treated with chemotherapy using platinum agents.1 Among patients with lymphoma and multiple myeloma, in particular, anemia risk is increased by these factors as well as the presence of persistent or resistant disease.1
The cause of anemia in cancer patients may vary.2 The production of red blood cells may be decreased because of anemia of chronic disease, which is mediated by the inflammatory cytokines interferon (IFN)-α, IFN-β, and IFN-γ, interleukin (IL)-1, IL-6, and tumor necrosis factor-α. Red blood cell production is also decreased by chemotherapy, bone marrow infiltration, myelosuppressive therapy, and chronic renal failure. Anemia can also be affected by nutritional deficiencies of iron, vitamin B12, and folate, along with severe protein calorie malnutrition. Acute and chronic blood loss due to bleeding, phlebotomy, hemolysis, and surgery may also contribute to the development of anemia.2
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Effects of Anemia
Consequences of anemia include impaired tissue oxygenation, impaired organ function, reduced quality of life, and greater postoperative mortality. Greater iron absorption stemming from ineffective erythropoiesis, higher probability of blood transfusion after chemotherapy, and lower sensitivity to chemotherapy also reflect the impact anemia may have in this patient group.1
Fatigue is heightened by anemia. Furthermore, anemia shortens survival in cancer patients, across almost all types of cancer studied.1 Anemia causes cardiac output to increase in order to maintain adequate oxygen delivery.2 Moreover, anemia impacts tumor behavior, since hypoxia induces changes in genes that promote angiogenesis and selects for p53 mutations to promote a more aggressive phenotype.1
An analysis of 500 adult cancer patients age 65 years and older found that 51% were anemic.3 Functional disability, which was defined as needing assistance with one or more instrumental activities of daily living, highly correlated with the presence of anemia. This study serves as just one example of the need to adequately treat anemia in cancer patients.3
Erythropoiesis-Stimulating Agents for Anemia
About half of cancer patients with nonmyeloid malignancies who are currently receiving myelosuppressive chemotherapy require red blood cell transfusions because of anemia and its symptoms.4 Erythropoiesis-stimulating agents (ESAs), among other agents, are used to treat anemia; however, ESAs increase hemoglobin concentrations, thereby potentially reducing the need for red blood cell transfusions.
Transfusions are associated with various risks such as acute reactions, transmission of an unknown infection, and even immunosuppression.2 ESAs come with risks as well. Choosing the appropriate ESA requires much consideration, particularly since they can increase the risk of thromboembolic events and stimulate tumor growth.4,5
