Taken together, these results suggest that USP28 deletion is a novel TP53 phenocopying alteration that commonly affects major cancer types such as breast cancer (6.2% of total breast tumors, not counting known phenocopying events and TP53 deletions) and also bladder, lung, liver and stomach cancer (7.6%, 7.0%, 3.8% and 2.9% cases, respectively). This evidence concerns the gene USP28 and gastric cancer.