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). Here, RB1 is linked to endometrial cancer.