PTEN and neoplasm: In support of this, Yuan et al. performed multiregional next-generation sequencing analysis on samples from spatially separated regions from two patients with oesophageal MiNEN to interrogate intra-tumour heterogeneity and clonal evolution; alterations in TP53, RB1, PTEN, PI3KCA, and KRAS were identified in all tumour samples/regions from both patients and had higher allele frequencies (compared to alterations not present in all samples/regions).