Renal cell carcinoma (RCC) has the propensity to lead to venous tumor thrombus (VTT). Nephrectomy with tumor thrombectomy is an effective treatment option but is a technically challenging surgical procedure that is accompanied by a high rate of complications. The aims of this study were to investigate pre-operative imaging parameters for the assessment of inferior vena cava (IVC) wall invasion due to a tumor thrombus in patients with RCC and to identify predictors from the intra-operative findings.
Clinical and imaging data were collected from 110 patients who underwent nephrectomy with IVC tumor thrombectomy (levels I-IV) for RCC and IVC tumor thrombus at the Peking University Third Hospital between May 2015 and March 2018. Univariable and multivariable logistic regression and receiver operating characteristic curves were used to assess the correlations between pre-operative imaging features and intra-operative macroscopic invasions of the IVC wall by tumor thrombus.
Among the 110 patients, 41 underwent partial or segmental resection of IVC. There were univariate associations of pre-operative imaging parameters that could be used to predict the need for IVC resection, including those of the Mayo classification, maximum anterior-posterior (AP) diameter of the renal vein at the renal vein ostium (RVo), maximum AP diameter of the VTT at the RVo and IVC occlusion. For the multivariable analysis, the AP diameter of the VTT at the RVo and IVC occlusion were associated with a significantly increased risk of invasion of the IVC wall by tumor thrombus. The optimum imaging thresholds included an AP diameter of the VTT at the RVo larger than 17.0 mm and the presence of IVC occlusion, with which we predicted invasions of the IVC wall requiring IVC resection. The probabilities of intra-operative IVC resection for patients without both independent factors, with an AP diameter of the VTT at the RVo larger than 17.0 mm, with IVC occlusion, and with both concurrent factors were 5%, 23%, 56%, and 66%, respectively.
An increase in the AP VTT diameter at the RVo and the presence of complete occlusion of the IVC are independent risk factors for a high probability of IVC wall invasion by tumor thrombus.

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