5-FU, 5-Fluorouracil; AC, Adenocarcinoma; AUC, Area under curve; BSA, Body surface area; CT, Computed tomography; CTV, Clinical target volume; CXCR4, Chemokine receptor type 4; Esophageal cancer; FDG, [18F]-fluorodeoxyglucose; FFPE, Formalin-fixed paraffin-embedded; GTV, Gross tumor volume; HIF-1α, Hypoxia-inducible factor 1-alpha; HNSCC, Head and neck squamous cell carcinoma; IgG, Immunoglobulin; Ki67, Tumor proliferation nuclear protein; MRI, Magnetic resonance imaging; Microscopic tumor extension; NRCHT +R, Neoadjuvant radiochemotherapy followed by resection; PD1, Programmed death 1 receptor; PET, Positron emission tomography; PTV, Planning target volume; R, Resection; RCHT, Radiochemotherapy; Radiochemotherapy; SCC, Squamous cell carcinoma; TME, Tumor microenvironment; Tumor microenvironment; UKD, University Hospital Carl Gustav Carus Dresden; Whole slide image analysis; p53, Tumor suppressor protein