proposed that erythrocytosis could result from sensitization to the effects of EPO and is a rebound to VEGF inhibition-induced hypoxia after observing reversible erythrocytosis in patients treated with sunitinib or sorafenib for different tumor types (renal cell carcinoma [RCC], melanoma, and hepatocellular carcinoma) (21). This evidence concerns the gene EPO and neoplasm.