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Impact Of Nephrectomy On Long Term Renal Function In Non-Syndromic Children Treated For Unifocal Wilms Tumor
Adam J. Kern, M.D., Joan S. Ko, M.D., Bhavik B. Shah, M.D., Heather N. DiCarlo, M.D., Michael A. Gorin, M.D., Mohamad E. Allaf, M.D., Ming-Hsien Wang, M.D..
Johns Hopkins, Baltimore, MD, USA.
Controversy exists as to the management of non-syndromic children with unifocal Wilms tumor. The surgeon must weigh the excellent oncologic outcome associated with radical nephrectomy against the impetus to preserve functional renal mass. The present study is designed to assess the long-term renal function of children who underwent radical nephrectomy for unifocal Wilms tumor. The authors hypothesize that factors related to type of intervention, such as exposure to adjuvant therapy, may be the primary determinants of long-term GFR.
A retrospective cohort study of non-syndromic children treated with radical nephrectomy for unifocal Wilms tumor at our institution between 1995 and 2011 was performed to identify risk factors for decreased GFR. The primary endpoint was decrease in calculated age-adjusted GFR below normal published ranges. The secondary endpoint was progression to chronic renal insufficiency (CRI). Continuous and categorical risk variables were evaluated using t-tests and Fisher’s exact test, respectively. Significant variables were further evaluated using regression analysis.
A total of 55 patients were identified in the cohort. Eight (15%) patients exhibited decreased age-adjusted GFR during the follow-up period, with 2 (4%) progressing to CRI. Patients with diminished GFR at the time of last follow-up were found to have a higher mean age at diagnosis in comparison to those with a normal GFR (5.6 years vs. 2.7 years; p=0.033). On regression analysis, each additional year in the age of diagnosis conferred a 1.24-fold increase in the odds of diminished long-term GFR (p=0.042). Median follow-up time between surgery and last GFR calculation was 6.3 years. Seven of the eight patients (88%) with diminished GFR had follow-up time greater than 6.3 years (p=0.022). Significance of these variables was confirmed on multivariate regression. Notably, higher tumor stage, unfavorable histology, adjuvant chemotherapy and contralateral renal irradiation were not found to have a significant impact on GFR.
A trend toward decline in GFR was detected with longer follow up. This suggests that any incremental decline in renal function seen shortly after nephrectomy may be just the tip of the iceberg. Longer follow-up may reveal that clinically significant decline in renal function, if present, manifests many years following nephrectomy. Additionally, intrinsic patient characteristics, such as age at initial presentation, significantly drive long-term GFR decline. Further study is needed to identify selection criteria for patients who are intrinsically suited for nephron sparing approach.
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