RB1 and gastrointestinal stromal tumor: Only a small percentage of tumors (~20%) displays distinct diagnostic markers: recurrent genetic alterations, such as specific mutations (e.g., KIT activating mutation in gastrointestinal stromal tumors) and chromosomal translocations (observed in approximately 20% of STSs), or complex genomic profiles and mutated tumor suppressor genes, including TP53 and retinoblastoma 1 (RB1) [9,13,14].