Ross et al. (2015) performed comprehensive genomic profiling for 200 patients with CUP and showed that mutations of human epidermal growth factor receptor 2 (HER-2) were more frequent in adenocarcinomas of unknown primary site (13 patients [10%]) than in non-adenocarcinomas of unknown primary site (3 patients [4%])44. This evidence concerns the gene ERBB2 and adenocarcinoma.