Figure 1. Inferior vena cava (IVC) tumour thrombi with changes (red arrows) revealed using computed tomography or magnetic resonance imaging in patients with renal cell carcinoma. (a-1, b-1, c-1, and d-1) Evaluation of IV tumour thrombi before combination treatment with immune checkpoint inhibitors (ICIs) in cases 1, 2, 3, and 4, respectively. (a-2, b-2, c-2, and d-2) The best responses of IVC tumour thrombi treated with ICIs was observed in cases 1, 2, 3, and 4, respectively. (c-3) Case 3: An increase in the pre-existing IVC tumour thrombi one month after ICI therapy interruption owing to an immune-related adverse event.