ERBB2 and esophageal squamous cell carcinoma: It currently consists mainly of immunohistochemically determined markers, namely the PD-L1 status (stated by the Tumor Proportion Score [TPS], Combined Positivity Score [CPS] and Tumor Area Proportion [TAP] Score) in esophageal squamous cell carcinomas, as well as the HER2 status (supplemented by in situ hybridization in case of equivocal results), the mismatch repair status (optionally supplemented by molecular pathological determination of microsatellite status), and, since mid-2024, the expression of claudin 18.2 in gastroesophageal adenocarcinomas.