CXCL8 and lung adenocarcinoma: In both the breast cancer cohort and the lung adenocarcinoma cohort, we found that high protein levels of all four factors (IL-8, PDGF-AA, Serpin E1, and MIF) were associated with significantly lower survival (p < 0.0001 and p < 0.05, respectively) (Fig. 4e, Additional file 1: Fig. S3).