When comparing pre‐treated with not pre‐treated dogs, the risk of tumour progression was significantly higher in pre‐treated dogs, whether calculated from the beginning of CHOP (HR: 1.6; 95% CI: 1.2–2.1; p = 0.003; Figure 1) or from the beginning of steroid administration (HR: 1.4; 95% CI: 1–1.8; p = 0.036). This evidence concerns the gene DDIT3 and neoplasm.