CXCL8 and cancer: Various biomarkers or molecules can be detected in saliva, e.g., the cytokines interleukin-6 [70,71], interleukin-8 mRNA [72,73,74], interleukin-8 protein [72,73,74], cancer antigens [48] like carcinoembryonic antigen (CEA) [75,76], cancer antigen 125 (CA125) [76] and Her-2/Neu (C-erbB-2) [76,77], VEGF165 [78], TNFα [79], or cytokeratin-19 antigen (Cyfra 21-1) [80].