POLE and endometrial cancer: For example, in the combined TCGA/LUMC endometrial cancer cohorts, truncating mutations in the tumour suppressors APC, NF1 and RB1 were very rare in POLE‐wild‐type tumours (1.1%, 1.5%, and 1.5%, respectively), but common among POLE‐mutant cases (38.8%, 34.7%, and 34.7%, respectively; p < 0.001 for each comparison, Fisher's exact test), in which they almost invariably occurred at glutamic acid or arginine codons (supplementary material, Figures S8–S10, and Tables S9 and S11).