Background: Wilms tumor (WT) is the commonest renal cancer during childhood. Intravascular extension is a well-recognized phenomenon in WT patients, usually involving renal vein and inferior vena cava (IVC), sometimes with invasion up to the right atrium. Most intracaval and intraatrial thrombi show a good response to preoperative chemotherapy. However, treatment of persistent intravascular extension represents a surgical challenge and may be associated with significant morbidity. Notably, there are no formal practice guidelines to define the optimal surgical treatment of IVC involvement, namely whether or not IVC resection allows better tumor clearance and whether or not vascular reconstruction after IVC resection is needed. Therefore, in the absence of representative studies, the aim of present study project is to determine the clinical profile of WT patients undergoing circumferential resection of the IVC with or without reconstuction, with special emphasis on their oncologic outcomes and procedure-related morbidity.
Methods: Multicenter, longitudinal observational study on WT patients receiving cavectomy as part of their surgical treatment for IVC involvement. Data collected will include patient demographics, stage of disease, laterality of renal primary, level of IVC extension, indications for cavectomy, histopathology, treatment received, morbidity and mortality. A special clinic follow-up will be arranged to obtain additional data and provide long-term outcomes into adulthood.
Hypothesis: In WT patients with IVC involvement and complete luminal occlusion, cavectomy without reconstruction is well tolerated because these patients have well-developed collaterals secondary to pre-existing IVC occlusion. IVC prosthetic replacement is a timeconsuming and technically demanding procedure that is not without complications.
The study will provide overall and relative estimates of the lifetime risk of developing lower extremity deep vein thrombosis in these patients.
As outlined in previous sections, this project aims to investigate a restricted cohort of patients affected by Wilms tumor (WT), which represents a rare malignant primary renal tumor during childhood, and vascular tumor involvement in the form of a thrombus extending into the inferior vena cava (IVC), which represents an even rarer occurrence affecting only 4-10% of WT patients. The treatment of chemotherapy-resistant intravascular extension of WT patients represents a surgical challenge and may be associated with significant morbidity. We will focus on the potential role of cavectomy (removal of a circumferential portion of the IVC) in WT patients with vascular involvement and dense thrombus adherence, which may render these thrombi not amenable to thrombectomy only. In this subset of patients, there are no formal practice guidelines to define the indications for IVC resection in order to achieve complete tumor clearance, and whether IVC resection is best coupled with or without vascular reconstruction is yet to be determined.
In the absence of representative studies, the aim of present study project is to determine the clinical profile of WT patients undergoing circumferential IVC resection with or without reconstruction, and to perform the first longitudinal study with special emphasis on the oncologic outcomes and procedure-related morbidity of these patients. Since the population of interest is relatively small, we designed a multicenter study to enhance patient recruitment.
Research Hypothesis: In WT patients with IVC involvement and complete luminal occlusion, cavectomy without reconstruction is well tolerated because these patients have well-developed collaterals secondary to pre-existing IVC occlusion. In contrast, IVC prosthetic replacement is a time-consuming and technically demanding procedure that is not without complications. Additionally, cavectomy may allow for complete tumor clearance, thus obviating the need of radiation therapy and decreasing the burden of treatment-related morbidity in some of these WT survivors. Finally, we should be able to provide the overall and relative estimates of the lifetime risk of developing lower extremity deep vein thrombosis (DVT) in this high-risk subset of patients, which is an information currently not available. Therefore, these findings will lay the groundwork for prevention of, screening for, and treatment of these patients at greater risk of lower extremity DVT.