Cancers are a common cause of death in old mice44, and gross autopsy data revealed fewer macroscopic tumours in mice with Il11 deletion (pooled sexes: wild-type, 49 out of 84 mice had tumours; Il11−/−, 3 out of 25 mice had tumours; P < 0.0001) or on anti-IL-11 therapy (pooled sexes: IgG, 22 out of 36 mice had tumours; X203, 3 out of 19 mice had tumours; P = 0.0013) (Supplementary Tables 6 and 7). This evidence concerns the gene IL11 and neoplasm.