IL6 and colorectal carcinoma: Patient serum levels of IL-6 have been associated with poor prognosis in many cancers, including CRC.29 IL-6 promotes cell survival and supports the production of vascular endothelial growth factor from both tumor and immune cells.29 Monocytes cultured in GM-CSF media with high IL-6, compared with no additional IL-6, had higher expression of CD163 and CD14.