Background: Whether partial nephrectomy (NSS) is a reasonable alternative to nephrectomy in children with Wilms tumor (WT) in the setting of a normal contralateral kidney remains controversial. Main issue against such clinical scenario is that there is no convincing evidence that 50% reduction of renal mass is associated with increased risk of renal failure. However, we have already produced robust data supporting the oncologic efficacy and safety of such approach, along with positive effect on long-term renal function in our cohort of children with non-metastatic WT.
Purpose: To validate the efficacy and safety of our clinical protocol of NSS in children with unilateral primary renal tumor and normal contralateral kidney. In particular, we will focus our attention on the oncologic and nephrological outcomes of NSS in our cohort of patients.
Methods: Single Institution, longitudinal and cross-sectional pilot study. Primary end points will include:
- To determine residual renal function and relative renal volume of the kidney remnants after NSS;
- To compare oncologic and nephrological outcomes of patients with primary renal tumor receiving either radical nephrectomy or NSS.
Matched case-control analysis will be employed to control for known potential confounding variables. We will also assess local and systemic recurrence rates, overall and event-free survival rates, and morbidity (especially surgery-related).
Hypothesis: Kidney remnants after NSS significantly contribute to overall renal mass and function. Such renal function advantage of NSS does not adversely affect the oncologic outcome of these patients, in comparison to patients treated with radical nephrectomy.
Implication: In children, nephrectomy should no longer be considered as the gold standard surgical treatment for unilateral WT, even in the setting of a normally functioning contralateral kidney.
As previously mentioned, in the proposed study all patients with unilateral kidney tumor treated at our center will be recruited. An electronically maintained database will be set up, including both patients enrolled prospectively from 1992 and those treated during the previous decades, collecting patients since the establishment of our center in 1939. The Municipal Archives of the city of Rome will be also searched to trace patients born during the initial decades of activity of our center. We estimate to recruit about 80 patients. The database will be filled with all available patients¿ clinical information, including laboratory and imaging studies data. The following parameters will be analyzed for the study: demographics including age at diagnosis and at surgery, pre- and post-operative renal function, type of surgery performed, neo-adjuvant and adjuvant chemotherapy, radiotherapy, tumor staging and histological findings. To assess renal function, we will calculate the estimated glomerular filtration rate (eGFR), which is widely accepted as the best surrogate marker of overall renal function. eGFR is actually calculated from serum creatinine values indexed not only to age and gender, but also to body size. Measurements of eGFR will be made using either the revised Schwartz equation or the equation from the Modification of Diet in Renal Disease study, as appropriate for age. A renal dysfunction will be defined as eGFR 150 mg/24 hours. Systemic blood pressure measurements will be also taken and values will be indexed by gender and age, and expressed as standard deviation scores, utilizing available values of systolic and diastolic pressure in the normal population. An ultrasonography, if not recently performed, will be repeated for kidney volume quantification. Standard deviations will be calculated using available normograms of renal volumes in both pediatric and adult population. The aims of present study project can be summarized as follows:
- To determine residual renal function and relative renal volume of the kidney remnants after NSS.
- To compare oncologic and nephrological outcomes of patients with primary renal tumor receiving either radical nephrectomy or NSS. Matched case-control analysis will be employed to control for known potential confounding variables. The obtained results from the proposed study will be very innovative and will contribute to expand the currently limited role of NSS for select children with unilateral primary renal tumor and normal opposite kidney.