CXCR4 and esophageal cancer: Our observation of in vivo imaging of CXCR4 expression in humans with both newly diagnosed as well as pre-treated, recurrent esophageal cancer suggest that chemokine receptor 4 (CXCR4) expression in esophageal cancer is not an unusual condition and can be assessed non-invasively by PET/CT and the CXCR4-directed radiopharmaceutical [68Ga]Pentixafor.