Successful interdisciplinary treatment of renal cell carcinoma with tumour thrombus into inferior vena cava using multimodal protocol and organ-extending R0 resection in rare horseshoe kidney and doubled right organ.

This is the first case ever reported showing a combination of renal cell carcinoma (RCC) with tumour thrombus into inferior vena cava (IVC), horseshoe kidney and doubled right kidney that was successfully treated. Even in advanced tumour lesions of the kidney, curative treatment is a feasible and safe option by using interdisciplinary cooperation and expertise. However, this requires an adequate diagnostic work-up to clarify resectability and optimal perioperative and postoperative care, and also advanced surgical skills exhausting all potential options for complete tumour resection in a centre of excellence. Achieving R0 resection with a reasonable risk-benefit ratio for the patient, which should be the primary aim, can distinctly improve survival chances as published cases in literature have indicated. RCC-derived IVC tumour thrombus as an extra-renal tumour manifestation by continuous intravascular tumour growth (also classified as secondary IVC tumour lesion) can be considered no serious contraindication to aim for curative surgery.