Cuevas D, Velasco A, Vaquero M, et al. - In order to discuss intratumor heterogeneity (ITH) analysis in endometrial serous carcinomas (ESC), researchers did a descriptive integrated molecular approach via targeted sequencing and multiplex ligation-dependent probe amplification (MLPA) to recognize mutations and somatic copy-number alterations (SCNA) patterns, respectively. Eight ESC were analyzed, choosing three tumor regions per case and their corresponding normal tissue. Targeted sequencing exhibited that in all tumor regions, mutations in TP53, PIK3CA and PPP2R1A were omnipresent. Furthermore, according to the previously known presence of genomic instability in ESC, MLPA results illustrated a high frequency of SCNA. Moreover, SCNA, unlike the homogeneous distribution of somatic mutations, showed ITH influencing targetable genes like ERBB2. Hence, this study implies that the main source of ITH in ESC are modifications in somatic gene copy-number.