Studies of EGFR inhibitors demonstrated an association of skin rash development with an improved therapy outcome in various cancer entities including colorectal carcinoma, head-and-neck squamous cell carcinoma, non-small cell lung cancer, prostate cancer, gastro-esophageal cancer, pancreatic adenocarcinoma and cutaneous squamous cell carcinoma (2, 3). This evidence concerns the gene EGFR and Skin rash.