Background/Objectives: To compare perioperative, pathological, functional, and oncological outcomes of robot-assisted radical nephrectomy with inferior vena cava tumor thrombectomy (RARN-TT) versus open (ORN-TT) and laparoscopic (LRN-TT) approaches. Methods: PubMed, Scopus, and Web of Science were searched for studies of adults with renal cell carcinoma and Mayo/Neves level I–IV inferior vena cava tumor thrombus undergoing RARN-TT versus ORN-TT and/or LRN-TT. Risk ratios and mean differences with 95% confidence intervals were calculated using random effects models with restricted maximum-likelihood estimation. Results: Eight retrospective studies including 1781 patients were included: 221 underwent robotic surgery, 1411 open surgery, and 149 laparoscopic surgery. Compared with ORN-TT, RARN-TT was associated with lower estimated blood loss (mean difference −900.5 mL, 95% confidence interval −1234.0 to −566.9; p = 0.001), lower transfusion probability (risk ratio 0.395, 95% confidence interval 0.159–0.979; p = 0.046), and shorter hospital stay (mean difference −3.79 days, 95% confidence interval −4.83 to −2.76; p < 0.001). No significant differences were observed in operative time, intensive care unit stay, postoperative complications, perioperative mortality, pathological outcomes, or overall survival. Evidence for cancer-specific and progression-free survival was limited. Comparisons with LRN-TT were exploratory. Conclusions: RARN-TT may reduce blood loss, transfusion requirements, and hospital stay compared with ORN-TT, without evidence of worse perioperative, pathological, or survival outcomes. However, all studies were retrospective and affected by selection bias and heterogeneity. RARN-TT may be considered for selected patients at experienced centers, particularly for lower-level thrombi. Prospective multicenter studies stratified by thrombus level are needed.

Introduction: Assessment of renal tissue and renal tumor stiffness may provide complementary information for tissue characterization; however, conventional imaging modalities such as multiphasic computed tomography (CT) do not directly quantify biomechanical properties. Elastography techniques, including magnetic resonance elastography (MRE) and ultrasound elastography (US-E), allow noninvasive measurement of tissue stiffness but are not routinely available in standard clinical practice. This study protocol aims to develop a CT-based stiffness mapping of renal parenchyma and renal tumors by investigating the relationship between CT attenuation values and elastography-derived stiffness measurements, using MRE and US-E as reference modalities. Methods and analysis: This monocentric, prospective, exploratory, non-randomized, and non-blinded diagnostic study will enroll 50 adults undergoing partial or radical nephrectomy for renal tumors at the University Hospital of Bordeaux. All participants will undergo a predefined multimodal imaging protocol—including contrast-enhanced CT, multiparametric magnetic resonance imaging (MRI) with -MRE and US-E—conducted between inclusion and the day before surgery. The primary objective is to construct a regression model predicting MRE-derived elasticity (μMRE) from CT density values using multiple machine-learning algorithms evaluated through repeated nested cross-validation. Secondary analyses will include voxel-level and region-of-interest correlations across modalities, feasibility and image-quality assessment of DWI-vMRE, repeatability of elastography measurements, identification of limiting factors such as BMI, sarcopenia, lesion location and architecture, evaluation of inter-modality de-correlation and associations with final histopathology (including subtype and grade). Trial registration: ClinicalTrials.gov identifier: NCT06525831 . Protocol ID-RCB: 2024-A00959-38. Recruitment began on 7 March 2025.