To explore impaired erythropoiesis and relative inadequacy of erythropoietin production in the anemic cancer patients and the correlation of tumor necrosis factor-alpha (TNF-alpha) or interferon-gamma (IFN-gamma) with inadequate erythropoietin (EPO) response and impaired erythropoiesis in cancer patients with anemia.
Fifty adult anemic and 15 non-anemic tumor patients were studied. Serum EPO levels were measured by radioimmunoassay (RIA) and serum soluble transferrin receptor (sTfR). TNF-alpha and IFN-gamma levels by enzyme-linked immunosorbent assay (ELISA). Log transformed EPO and sTfR values were used in statistical analysis. The R correlation analyses were performed.
The mean serum immunoreactive erythropoietin level in anemic cancer patients [(23.11 +/- 10.00) IU/L] was not significantly higher than in healthy people (P = 0.053), but significantly lower than in IDA patients with similar degree of anemia [(43.00 +/- 22.00) IU/L, P < 0.01]. Both O/P EPO [0.88 (0.54-1.10)] and O/P sTfR [0.89 (0.57-1.22)] were significantly lower in anemic cancer patients than in controls and in non-anemic cancer patients. There was no significant difference between the latter two groups. Furthermore, the expected inverse linear relation between serum EPO and hemoglobin levels was absent in the anemic cancer patients, and so did the relation between serum sTfR and hemoglobin levels. There was no correlation between O/P EPO and O/P sTfR. The serum levels of both TNF-alpha and IFN-gamma in anemic cancer patients [(25.75 +/- 26.71) ng/L, (50.49 +/- 42.12) ng/L, respectively] were significantly higher than those in healthy controls (both P < 0.01) or in nonanemic cancer patients (both 0.01 < P < 0.05), and so did between non-anemic cancer patients and controls. The serum levels of TNF-alpha were inversely correlated with hemoglobin levels (r = - 0.40, P = 0.004), O/P EPO (r = -0.32, P = 0.025) or O/P sTfR (r = -0.36, P = 0.01); while serum levels of IFN-gamma were inversely correlated with hemoglobin levels (r = -0.36, P = 0.01) or O/P sTfR (r = 0.39, P = 0.006), but not with O/P EPO. Conclusions Anemia of cancer is due to impaired erythropoiesis and relative inadequacy of EPO production. TNF-alpha might inhibit EPO production and erythropoiesis, while IFN-gamma maybe directly inhibit erythropoiesis and be independent of EPO response inadequacy.