Moreover, multivariate analyses suggested that apart from the number of lung metastases, the maximal diameter of lung metastases, the pathologic grade and anemia, infiltration of ≥2.5-fold increase in the percentage of CD163+EPOR+ TAMs was still considered an independent prognostic factor in osteosarcoma lung metastases for both mDFS and mOS (hazard ratio [HR] = 2.3, P < 0.0001 and HR = 1.6, P = 0.003). This evidence concerns the gene EPOR and anemia.