Endogenous erythropoietin and erythropoietin receptors in colorectal cancer; can we answer the questions?

Erythropoietin (Epo) is glycoprotein hormone which binds on erythropoietin receptors (EpoR) promoting proliferation and differentiation. Studies have shown that EpoR, apart from erythrocyte precursors, is expressed on no hematopoietic tissue and various tumor cells. Despite the progress in modern medicine, colorectal carcinoma (CRC) is still the leading cause of increased morbidity and mortality between oncology patients worldwide. Its precursors are benign villous adenomas, which in certain percentage progress to cancer. Anemia of chronic disease is common finding in CRC patients. Some of them are treated with Epo. Epo/EpoR seems to correlate with tumor progression and metastasizing. Therefore, the identification of at-risk group remains a clinical challenge. Vascular endothelial growth factor (VEGF) is a signal protein that stimulates angiogenesis and concentration of VEGF is positive correlated with tumor growth in numerous tumors. The importance of Epo in tumor pathogenesis has led to a growing interest in the potential prognostic value. By our point of view there are many open questions about role of Epo/EpoR in CRC.