Abstract
Objectives
To compare and contrast the use of partial nephrectomy (PN) and radical nephrectomy (RN) in pediatric malignant renal tumors using a nationally representative database.
Methods
The 2010–2014 Nationwide Readmissions Database (NRD) was used to obtain PN and RN select postoperative data. ICD-9-CM codes were used to identify children (<10 y), adolescents (10–19 y) and young adults (20–30 y) diagnosed with malignant renal tumors who were treated with a PN or RN. The presence of a 30-day readmission, occurrence of post-operative complications, cost, and length of stay (LOS) were studied and weighted logistic regression models were fit to test for associations.
Results
There were 4330 weighted encounters (1289 PN, 3041 RN) that met inclusion criteria: 50.8% were children, 7.2% were adolescents, and 42% were young adults. Young adults had the highest rates of PN, whereas children had the highest rates of RN (p<0.0001). Overall, no evidence was found to suggest a difference in odds between surgical modality and the presence of a 30-day readmission or postoperative complication. While PN was on average $9,000 cheaper compared to RN overall, its cost was similar to that of RN for children. Similarly, PN patients had a shorter overall LOS compared to RN patients, but their LOS was similar to that of children who underwent RN.
Conclusion
There was no evidence of a difference in odds between RN and PN in terms of postoperative readmissions or in-hospital complication rates. Additionally, we observed descriptive differences in both cost and LOS between the surgical modalities across age groups.
Type of Study
Retrospective comparative study (administrative database analysis)
Level of Evidence
Level III
Keywords: Wilms Tumor, Partial nephrectomy, Radical nephrectomy, Postoperative complications
Introduction
Radical nephrectomy (RN) has long been the gold standard for surgical management of most pediatric renal tumors.[1] However, increasing evidence suggests that RN may predispose to chronic kidney disease.[2] As a result, there has been a growing interest in partial nephrectomy (PN) as a means of potentially improving long-term mortality and delaying end stage renal disease in select conditions.[3, 4] Preserving renal function is particularly important in children, given that their extended life expectancy places them at risk for complications for decades beyond the conclusion of their treatment.[4, 5]
Despite the mounting evidence for PN, it continues to be used far less frequently than RN in children.[6–10] The reasoning behind this relative underutilization is not entirely clear. Previous studies have found that RN and PN are similar in terms of survival [6, 9, 10] and in-hospital complications.[6, 9] Adult studies suggest that while RN and PN have similar short-term costs, RN may be far more expensive when considering the increased long-term burden of end-stage renal disease.[11] However, the specific complications that may occur following PN (e.g., urine leak) could ostensibly lead to higher readmissions,[12] which might explain some of the disparity between RN and PN usage.
To better characterize practice patterns between these modalities, we aimed to compare the rates of postoperative complications and 30-day readmissions, costs, and length of stay following RN and PN in children, adolescents, and young adults for malignant masses. We used a database specifically designed to study nationally-representative trends in readmissions, which has the unique advantage of tracking longitudinal patient-specific data on a national scale in order to analyze patient-specific readmission rates. Given that PN is a more technically demanding procedure than RN, we hypothesized that PN would have a higher 30-day readmission rate and higher postoperative complication rate compared to RN for all age groups.
Material & Methods
Data Source
The 2010 to 2014 Nationwide Readmissions Database (NRD) was used to abstract the study population. The NRD was created to analyze national readmission rates while adhering to strict privacy guidelines. The NRD is derived from 21 of the HCUP State Inpatient Databases (SID). These 21 states are geographically dispersed and account for approximately 49% of all U.S. hospitalizations. The sample includes both children’s and adult hospitals, based on 5 hospital characteristics such as teaching status and location.[13] Weights are applied to the sample to make national level inferences. Weighted estimates are non-integer values that must be rounded. This may result in slightly different weighted totals when examining different variables. Patients cannot be tracked across years in the NRD, thus each year must be treated as a stratum.
Inclusion Criteria
All patient encounters were identified in the NRD between 2010 and 2014 between the ages of 0 and 30 with an International Classification of Disease (ICD)-9 code for malignant renal tumor (189.0) and either a radical (55.5) or partial (55.4) nephrectomy. Patients identified with ICD-9 codes for malignant urological tumors outside the kidney (189.1–189.9), benign urological tumors (223.1–223.9; 236.90; 236.99), having undergone both RN and PN (indicating possible bilateral disease), or encounters admitted in December (since they may not have had 30 days of follow-up) were excluded. Covariates included were gender, insurance, median quarterly income, hospital type, year of admission, and Rhee Comorbidity Index (RCI).
Variable Definitions
There is a substantial difference in prevalence of malignant renal tumors by age: Wilms’ tumor is the most common pathologic entity among children while renal cell carcinoma is more prevalent among adults.[14] NRD uses ICD-9 codes, which provide non-specific codes for malignant renal tumors and thus lacks the ability to differentiate among the diagnoses encompassed within those codes. Patients were therefore grouped into categories based on age: children 0–9 years old (n=2200), adolescents 10–19 years old (n=311), and young adults 20–30 years old (n=1819) to approximate the tumor type.
The primary outcome of this study was the presence of at least one 30-day inpatient readmission and the secondary outcome was the occurrence of at least one postoperative complication, such as pneumonia or postoperative bleeding (Supplementary Table 1). These postoperative complications were identified using the ICD-9 codes that most closely corresponded to expected surgical complications as defined by the National Surgical Quality Improvement Program.[15] In addition, we identified nephrectomy-associated complications that would hypothetically make a patient more likely to be readmitted,[16] including urinoma, ileus, or bowel obstruction (Supplementary Table 2).
Inpatient length of stay and cost were examined by tumor type and age group. Cost was estimated by using the HCUP cost-to-charge ratio (CCR) files.[17] The RCI was used to measure and account for patient comorbidity.[18] This index was specifically developed to predict in-hospital mortality for pediatric surgical patients, where lower values represent lower risk patients and higher values represent higher risk patients. The RCI was calculated using ICD-9 codes and incorporates weighted comorbidities that are summed into a final score.
Statistical Analysis
Weighted descriptive statistics were utilized per HCUP recommendations to describe each surgical cohort (RN vs. PN), to account for NRD’s complex structure, and to make national level inferences.[13] Wald-chi-squared was used for discrete variables and weighted ANOVA was used for continuous variables to determine statistical significance between demographic characteristics. If a cohort did not have an observation in a subcategory of a variable, a Wald-chi-squared could not be calculated and Fisher’s exact test was used. Cell counts that were less than 15 were excluded as per HCUP data use agreement.[13]
For the primary outcome, 30-day readmission rate, a weighted logistic regression model was fit. The model adjusted for age, gender, insurance type, median quarterly income, hospital type, and RCI. A likelihood ratio test was used to determine if the interaction between age and surgery should be included; evidence was found to suggest the interaction term should be retained in the final model. Surgery type was the primary predictor. An effect on surgery performed for each age group was tested separately; a Bonferroni correction was implemented and the alpha was changed to 0.017. As a sensitivity analysis, the same primary model was fit while adjusting for nephrectomy-associated complications.
A weighted logistic regression model was fit for the secondary outcome, postoperative complications, and was adjusted for the same covariates as the primary model. As a post-hoc analysis, nephrectomy-associated complications was modeled, adjusting for the same covariates and using the same primary predictor as the primary model. Bonferroni correction was again used for both the secondary and post-hoc analysis. SAS 9.4 was used for all analyses.
Results
Demographics
There were 4,330 patients who met inclusion criteria for analysis; 29.8% underwent PN and 70.2% underwent RN. Of our cohort, 49.8% were female, 54.9% had private insurance, 89% were seen at a metropolitan teaching hospital, and 29.9% of patients had an RCI score ≥1. Young adults had the highest rates of PN (53.1% vs. 11.3% in children and 24.1% in adolescent). Conversely, children had the highest rates of RN (88.7% vs. 75.9% adolescent and 46.9% in young adult; p<0.01) (Table 1).
Table 1.
Patient characteristics of RN vs. PN.
| Partial Nephrectomy (n=1289) | Radical Nephrectomy (n=3041) | Total (N=4330) | p value | |
|---|---|---|---|---|
| Age Groups (n, %) | <.011 | |||
| Children | 249 (19.3%) | 1951 (64.2%) | 2200 (50.8%) | |
| Adolescent | 75 (5.8%) | 236 (7.8%) | 311 (7.2%) | |
| Young Adults | 965 (74.9%) | 854 (28%) | 1819 (42%) | |
| Age at Admission (y) | <.012 | |||
| Mean (SE) | 21.6 (0.9) | 10.6 (0.5) | 13.9 (0.6) | |
| Range | (0, 30) | (0, 30) | (0, 30) | |
| Median (IQR) | 25.7 (18.9, 28) | 4.5 (1.8, 21.3) | 7.8 (2.4, 26.1) | |
| Gender | 0.291 | |||
| Male | 614(47.7%) | 1560 (51.3%) | 2174 (50.2%) | |
| Female | 674(52.3%) | 1481 (48.7%) | 2156 (49.8%) | |
| Year | 0.231 | |||
| 2010 | 198(15.4%) | 567 (18.6%) | 765 (17.7%) | |
| 2011 | 240(18.6%) | 618 (20.3%) | 858 (19.8%) | |
| 2012 | 358(27.8%) | 587 (19.3%) | 945 (21.8%) | |
| 2013 | 265(20.5%) | 568 (18.7%) | 832 (19.2%) | |
| 2014 | 228(17.7%) | 702 (23.1%) | 930 (21.5%) | |
| Insurance | <0.011 | |||
| Public | 414(32.2%) | 1328 (43.7%) | 1742 (40.2%) | |
| Private | 820(63.6%) | 1555 (51.1%) | 2375 (54.9%) | |
| Other/Missing | 55(4.2%) | 158 (5.2%) | 213 (4.9%) | |
| Median Household | 0.351 | |||
| Incomes+ | ||||
| Q1 | 289 (22.4%) | 855 (28.1%) | 1145 (26.4%) | |
| Q2 | 362 (28.1%) | 850 (27.9%) | 1212 (28%) | |
| Q3 | 337 (26.2%) | 683 (22.5%) | 1021 (23.6%) | |
| Q4 | 274 (21.3%) | 610 (20%) | 883 (20.4%) | |
| Missing | 26 (2%) | 43 (1.4%) | 69 (1.6%) | |
| Hospital Type | 0.201 | |||
| Metropolitan non-teaching | 139(10.8%) | 286(9.4%) | 424 (9.8%) | |
| Metropolitan | 1123 (87.2%) | 2731(89.8%) | 3854 (89%) | |
| Teaching Non-metropolitan hospital | 27(2.1%) | 25 (0.8%) | 51 (1.2%) | |
| Rhee Score | 0.211 | |||
| 0 | 943 (73.1%) | 2093 (68.8%) | 3035 (70.1%) | |
| ≥1 | 346 (26.9%) | 948 (31.2%) | 1294 (29.9%) | |
| Rhee Score | 0.582 | |||
| Mean (SE) | 0.4 (0.05) | 0.5 (0.03) | 0.4 (0.03) | |
| Range | (0, 5) | (0, 12) | (0, 12) | |
| Median (IQR) | 0 (0, 0.1) | 0 (0, 0.3) | 0 (0, 0.2) |
Wald Chi-squared
Weighted ANOVA
Note that due to the NRD weighting algorithms, total patient counts can vary among the various columns.
Derived as the median household income of residents in the patient’s ZIP code. The quartiles indicate the poorest (Q1) to wealthiest populations (Q4). It is derived from ZIP Code-demographic data obtained from Claritas.
n – number of weighted encounters within a subgroup
N – total number of weighted encounters y – age in years
SE – Standard error of the mean
IQR – Inner quartile range
Clinical Outcomes
Among our overall cohort 18.4% had at least one 30-day inpatient readmission, 12.4% had a postoperative complication, and 19% had a nephrectomy-associated complication. Overall, PN was on average cheaper than RN ($18,507 [SE: $1,399.55] vs. $27,798 [SE: $1,237.87]; p<0.01). Patients who underwent PN also had on average a lower length of stay compared to those who underwent RN (4.1 [SE: 0.24] vs. 7.6 [SE: 0.24]; p<0.01) (Table 2).
Table 2.
Postoperative clinical outcomes of RN vs. PN.
| Partial Nephrectomy (n= 1289) | Radical Nephrectomy (n= 3041) | Total (N=4330) | p value | |
|---|---|---|---|---|
| 30 Day Inpatient | 173 (13.4%) | 622 (20.5%) | 795 (18.4%) | <0.011 |
| Readmissions | ||||
| 0 | 1116 (86.6%) | 2419 (79.5%) | 3535 (81.6%) | |
| 1 | 131 (10.2%) | 480 (15.8%) | 611 (14.1%) | |
| ≥2 | 42 (3.2%) | 142 (4.7%) | 184 (4.2%) | |
| Postoperative Complications | 146 (11.3%) | 391 (12.8%) | 537 (12.4%) | 0.511 |
| Nephrectomy-Associated Surgical Complications | 177 (13.7%) | 644 (21.2%) | 821 (19%) | <0.011 |
| Cost | <.012 | |||
| Mean (SE) | $18,507 ($1,399.55) | $27,798 ($1,237.87) | $25,009 ($1,042.16) | |
| Range | $775.56, $163,961 | $2,807.84, $43,1536 | $775.56, $431,536 | |
| Median (IQR) | $14,296 ($10,694, $21,006) | $21,116 ($13,832, $31,162) | $18,723 ($12,213, $28,539) | |
| Length of Stay | <.012 | |||
| Mean (SE) | 4.1 (0.24) | 7.6 (0.24) | 6.6 (0.20) | |
| Range | 0, 27 | 1, 103 | 0, 103 | |
| Median (IQR) | 2.8 (1.8, 4.4) | 5.6 (3.4, 8.2) | 4.5 (2.7, 7.3) |
Wald Chi-squared
Weighted ANOVA
Note that due to the NRD weighting algorithms, total patient counts can vary among the various columns.
n – number of weighted encounters within a subgroup N – total number of weighted encounters
SE – Standard error of the mean
IQR – Inner quartile range
We also examined cost and length of stay for each surgery by age. PNs and RNs had similar average costs for children ($34,354 [SE: $4,019.99] and $31,779 [SE: $1,775.69] respectively) and young adults ($14,362 [SE: $469.45] and $17,618 [SE: 906.58]). PNs were cheaper for adolescents compared to RNs ($19,292 [SE: $2,920.33] and $33,055 [SE: $2,896.83]). PNs on average had the longest length of stay for children (7.7 [SE: 0.64]) compared to adolescent (4.4 [0.50]) and young adults (3.2 [0.10]) (p<0.01). RNs and PNs had on average similar lengths of stay for children. These results suggest that age may be an important factor to consider when studying cost and length of stay for RNs and PNs (Appendix Table 1).
In the primary model, we did not find statistical evidence to conclude that there is a difference in the odds for surgical modalities and 30-day readmission rates for all age groups. In the secondary model, there was insufficient evidence to suggest an association between postoperative complication rates and surgical modality. On sensitivity analysis, there was also insufficient evidence of an association between nephrectomy-associated complications rates and surgical modality (Table 3).
Table 3.
Multivariate analysis of RN vs. PN by age (OR, 95% CI)
| Outcomes | Children | p value | Adolescent | p value | Young Adult | p value |
|---|---|---|---|---|---|---|
| 30-day readmission (y/n) | 1.41 (0.66, 3.03) | 0. 38 | 0.38 (0.12, 1.2) | 0.10 | 0.98 (0.55, 1.76) | 0.96 |
| Postoperative complications (y/n) | 0.91 (0.40, 2.06) | 0.82 | 4.67 (0.63, 34.8) | 0.13 | 1.02 (0.59, 1.78) | 0.93 |
| Nephrectomy-Associated complications (y/n) | 1.03 (0.57, 1.89) | 0.91 | 2.32 (0.41, 13.02) | 0.34 | 1.49 (0.87, 2.56) | 0.15 |
Model adjusted for gender, insurance type, median quarterly income, hospital type, RCI and nephrectomy associated complications. Surgery performed and age group was included in the model.
OR – Odds Ratios
CI – Confidence interval
Discussion
We compared hospital readmission rates of PN vs RN on a nationally representative scale. We did not find evidence of a difference between the type of nephrectomy performed and any of the clinical outcomes of interest: 30-day inpatient readmission rates, postoperative complications, or nephrectomy-associated complications. Cost and length of stay were on average lower for PN compared to RN.
Consistent with our expectations, we found that children had the highest rates of RN, while young adults had the highest rates of PN. Most WT occur in young children and are more amenable to RN than PN, though the proportion of tumors that are potential candidates for PN varies among studies; this is heavily influenced by tumor size and whether neoadjuvant chemotherapy is used, for example.[7, 8, 19, 20] Renal cell carcinoma, by contrast, is rare in children [21] and is typically diagnosed earlier in young adults compared to older adults,[22] making it more amenable to PN.
We expected higher 30-day readmission and postoperative complication rates in all age groups for PN. In this dataset, there was not statistical evidence of an association between surgical modality and 30-day readmissions or postoperative complication rates. Our hypotheses were motivated by the idea that PN is a technically demanding procedure that was potentially associated with specific complications that would increase readmissions. However, our analyses revealed no evidence that PN was associated with these types of complications. Our findings are similar to previous studies that failed to find evidence of a difference in overall complication rates between RN and PN.[6, 9]
Additionally, we observed descriptive differences in both cost and length of stay between the surgical modalities across age groups. While PN was on average $9,000 cheaper compared to RN overall, its cost was similar to that of RN for children. Similarly, PN patients overall had a shorter average length of stay compared to RN patients, but their average length of stay was similar to the sub-cohort of children who underwent RN (Table 2). An explanation for this similarity in cost and length of stay for children specifically is that surgeons may be more cautious and delay discharge in younger children undergoing PN.
Although PN is widely used in adults, its use in children remains uncommon.[6, 10, 22, 23] For practical reasons, regional and national population-level analyses detailing RN and PN outcomes in the pediatric population are scarce.[9] The utilization of PN in cases where either type of surgery is feasible, such as in cases of unilateral non-syndromic pediatric renal tumors, has primarily been limited to single institutional reports.[7, 19, 24] Previous studies have differed on how frequently PN is feasible for Wilms patients, ranging from 8 to 25%.[7, 8] Even in cases where PN is feasible, a frequent argument against the use of PN is the potential increased risk of positive margins.[25] However, published reports of PN for Wilms have not demonstrated an increased risk of local recurrence even in the setting of positive surgical margins.[19]
Surgeons are understandably averse to changing an established standard of care, particularly in children. It can be difficult to alter practice in a limited, high-risk population when there is a lack of high-quality evidence to support such a change, particularly given the well-documented excellent outcomes of RN. While administrative data such as these can provide support that outcomes after PN and RN are relatively similar, they are limited by the inherent selection bias of observational data. As such, these data cannot be interpreted to provide proof of superiority of PN nor RN, nor do they provide definitive guidance for pediatric surgeons and oncologists attempting to decide what technique should be used in a given child. Unfortunately, a randomized controlled trial comparing these surgical modalities is unlikely to be performed in children, preventing the definitive establishment of a superior surgical approach. Ultimately, the type of nephrectomy performed is often based on the surgeon’s preference and/or tumor characteristics.[26, 27]
Our results should be interpreted in light of their limitations. First, NRD does not capture tumor-specific data such as stage, size, chemotherapy treatments, or histology. These data would potentially affect the preferred method of surgery, as certain tumor characteristics (e.g., large tumor size or neoadjuvant chemotherapy use) may predispose to one treatment over another. In a prior study, Wilms’ tumor patients selected for PN were, in fact, more likely to have lower-staged tumors.[7]
Second, though NRD is geographically diverse, the results may not be generalizable as not all states are included. Third, the postoperative complications that we identified via ICD-9 codes may in some cases represent comorbidities. NRD does not allow investigators to distinguish temporal relationship among ICD-9 codes; thus, comorbidities that were present before surgery are indistinguishable from new onset comorbidities following surgery. Additionally, we cannot exclude human error caused by inconsistent coding.
Fourth, since this is a retrospective study we are limited to an analysis of associations. Encounters within each year of the NRD do not link across calendar years. We are therefore unable to track patients beyond December of each year since they may not have 30 days of follow-up. This was accounted for in the analysis by excluding encounters in December. By extension, we also cannot evaluate the effect of pre-surgical referral patterns on patients in NRD.
Fifth, our analysis relies upon ICD-9 procedure codes; while there are specific codes for RN and PN, it can be challenging to reliably differentiate between open vs. minimally-invasive RN or PN.[28] We did not attempt to account for surgical modality beyond RN or PN, both because of this technical challenge and because of the rarity of minimally-invasive techniques in pediatric renal tumors.[29] While it is possible that minimally-invasive surgical techniques may have been used in some of these patients (potentially influencing cost and length-of-stay outcomes), we have no reason to believe that these techniques would have been disproportionately used among RN or PN patients.
Finally, it is assumed that any readmission was a result of a surgically-related complication, when in reality readmissions may be caused by other unrelated factors (e.g., trauma, unrelated medical illness), potentially resulting in overestimation of readmission rates. We would anticipate that such random events would have contributed equally to both arms and nevertheless validates comparisons of the two. Likewise, chemotherapy is frequently given in the postoperative period, but reason for admission is not reliably coded in NRD. While we would not anticipate that this would bias our results (neither RN nor PN should differentially impact adjuvant chemotherapy admissions), it is possible that at least some of the readmissions we captured were in fact planned admissions for adjuvant chemotherapy.
Despite these limitations, our study expands on the extant literature suggesting there is not statistical evidence of a difference in short-term outcomes between PN and RN in children. In cases where either RN or PN may be employed, PN may be more desirable given the possible benefit of better long-term renal function and comparable outcomes overall.[10] Additionally, long-term outcomes, particularly oncologic outcomes, require further study to help inform practice changes.
Conclusions
There was not sufficient evidence of a difference between PN and RN when evaluating the quality measures of postoperative readmissions or complications for all age groups. Our results serve to provide evidence that future study should be conducted to validate the safety of PN as an alternative to RN for malignant non-syndromic pediatric renal masses.
Supplementary Material
Funding Acknowledgement
Dr. Routh is supported in part by grant K08-DK100534 from the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). The Duke Biostatistics Core’s support of this project was made possible (in part) by Grant Number UL1TR001117 from the National Center for Advancing Translational Sciences (NCATS), a component of the National Institutes of Health (NIH), and NIH Roadmap for Medical Research. Its contents are solely the responsibility of the authors and do not necessarily represent the official view of NCATS or NIH. The funding sources had no role in the collection, analysis and interpretation of data; in the writing of the manuscript; or in the decision to submit the manuscript for publication.
Appendix Table 1.
Cost and length of stay for RN and PN compared across age groups.
| Children | Adolescent | Young Adult | P-value | |
|---|---|---|---|---|
| PN Cost ($) | <.011 | |||
| Mean (SE) | 34354 (4019.99) | 19292 (2920.33) | 14362 (469.45) | |
| Range | 775.56, 163961 | 1544.20, 46700 | 1583.50, 51817 | |
| Median (IQR) | 28284 (18586, 39021) | 16263 (10748, 23323) | 12724 (10470, 16650) | |
| RN Cost ($) | <.011 | |||
| Mean (SE) | 31779 (1775.69) | 33055 (2896.83) | 17618 (906.58) | |
| Range | 4629.62, 431536 | 5106.87, 212444 | 2807.84, 221073 | |
| Median (IQR) | 23919 (17321, 34552) | 26268 (14968, 34618) | 13186 (9495.65, 20132) | |
| PN Length of Stay (d) | <.011 | |||
| Mean (SE) | 7.7 (0.6) | 4.4 (0.5) | 3.2 (0.1) | |
| Range | 0, 27 | 1, 8 | 1, 9 | |
| Median (IQR) | 5.7 (3.7, 8.0) | 4.1 (2.3, 5.0) | 2.5 (1.6, 3.6) | |
| RN Length of Stay (d) | <.011 | |||
| Mean (SE) | 8.6 (0.3) | 8.6 (1.1) | 5.0 (0.3) | |
| Range | 2, 103 | 1, 63 | 1, 43 | |
| Median (IQR) | 6.5 (4.6, 8.9) | 5.4 (3.1, 12.0) | 3.0 (1.8, 5.3) |
Weighted ANOVA
n – number of weighted encounters within a subgroup N – total number of weighted encounters
SE – Standard error of the mean
IQR – Inner quartile range
Footnotes
Ethical Approval: This protocol was reviewed by our Institutional Review Board and deemed to not be humans subject research, thus exempt from review.
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REFERENCES
- [1].Green DM, Breslow NE, Beckwith JB, Ritchey ML, Shamberger RC, Haase GM, et al. Treatment with nephrectomy only for small, stage I/favorable histology Wilms’ tumor: a report from the National Wilms’ Tumor Study Group. J Clin Oncol 2001;19(17):3719–24. [DOI] [PubMed] [Google Scholar]
- [2].Huang WC, Levey AS, Serio AM, Snyder M, Vickers AJ, Raj GV, et al. Chronic kidney disease after nephrectomy in patients with renal cortical tumours: a retrospective cohort study. Lancet Oncol 2006;7(9):735–40. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [3].Go AS, Chertow GM, Fan D, McCulloch CE, Hsu CY. Chronic kidney disease and the risks of death, cardiovascular events, and hospitalization. N Engl J Med 2004;351(13):1296–305. [DOI] [PubMed] [Google Scholar]
- [4].Cotton CA, Peterson S, Norkool PA, Takashima J, Grigoriev Y, Green DM, et al. Early and late mortality after diagnosis of wilms tumor. J Clin Oncol 2009;27(8):1304–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [5].Cozzi DA, Ceccanti S, Frediani S, Mele E, Cozzi F. Renal function adaptation up to the fifth decade after treatment of children with unilateral renal tumor: a cross-sectional and longitudinal study. Pediatr Blood Cancer 2013;60(9):1534–8. [DOI] [PubMed] [Google Scholar]
- [6].Chu DI, Lloyd JC, Balsara ZR, Wiener JS, Ross SS, Routh JC. Variation in use of nephron-sparing surgery among children with renal tumors. J Pediatr Urol 2014;10(4):724–9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [7].Cost NG, Lubahn JD, Granberg CF, Sagalowsky AI, Wickiser JE, Gargollo PC, et al. Pathological review of Wilms tumor nephrectomy specimens and potential implications for nephron sparing surgery in Wilms tumor. J Urol 2012;188(4 Suppl):1506–10. [DOI] [PubMed] [Google Scholar]
- [8].Ferrer FA, Rosen N, Herbst K, Fernandez CV, Khanna G, Dome JS, et al. Image based feasibility of renal sparing surgery for very low risk unilateral Wilms tumors: a report from the Children’s Oncology Group. J Urol 2013;190(5):1846–51. [DOI] [PubMed] [Google Scholar]
- [9].Vanden Berg RN, Bierman EN, Noord MV, Rice HE, Routh JC. Nephron-sparing surgery for Wilms tumor: A systematic review. Urol Oncol 2016;34(1):24–32. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [10].Wang HH, Abern MR, Cost NG, Chu DI, Ross SS, Wiener JS, et al. Use of nephron sparing surgery and impact on survival in children with Wilms tumor: a SEER analysis. J Urol 2014;192(4):1196–202. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [11].Klinghoffer Z, Tarride JE, Novara G, Ficarra V, Kapoor A, Shayegan B, et al. Cost-utility analysis of radical nephrectomy versus partial nephrectomy in the management of small renal masses: Adjusting for the burden of ensuing chronic kidney disease. Canadian Urological Association journal = Journal de l’Association des urologues du Canada 2013;7(3–4):108–13. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [12].Zaid HB, Parker WP, Lohse CM, Cheville JC, Boorjian SA, Leibovich BC, et al. Patient factors associated with 30-day complications after partial nephrectomy: A contemporary update. Urol Oncol 2017;35(4):153 e1–e6. [DOI] [PubMed] [Google Scholar]
- [13].Shanks GD, Waller M, Briem H, Gottfredsson M. Age-specific measles mortality during the late 19th-early 20th centuries. Epidemiol Infect 2015;143(16):3434–41. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [14].Howlader NNA, Krapcho M, Garshell J, Miller D, Altekruse SF, Kosary CL, Yu M, Ruhl J, Tatalovich Z, Mariotto A, Lewis DR, Chen HS, Feuer EJ, Cronin KA (eds). SEER Cancer Statistics Review, 1975–2012, National Cancer Institute, https://seer.cancer.gov/archive/csr/1975_2012/results_merged/sect_29_childhood_cancer_iccc.pdf; [accessed 29 March.2017]. [Google Scholar]
- [15].Khuri SF, Daley J, Henderson W, Hur K, Demakis J, Aust JB, et al. The Department of Veterans Affairs’ NSQIP: the first national, validated, outcome-based, risk-adjusted, and peer-controlled program for the measurement and enhancement of the quality of surgical care. National VA Surgical Quality Improvement Program. Annals of surgery 1998;228(4):491–507. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [16].Stephenson AJ, Hakimi AA, Snyder ME, Russo P. Complications of radical and partial nephrectomy in a large contemporary cohort. J Urol 2004;171(1):130–4. [DOI] [PubMed] [Google Scholar]
- [17].Zhang W, Song TQ, Zhang T, Wu Q, Kong DL, Li Q, et al. Adjuvant interferon for early or late recurrence of hepatocellular carcinoma and mortality from hepatocellular carcinoma following curative treatment: A meta-analysis with comparison of different types of hepatitis. Mol Clin Oncol 2014;2(6):1125–34. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [18].Rhee D, Salazar JH, Zhang Y, Yang J, Yang J, Papandria D, et al. A novel multispecialty surgical risk score for children. Pediatrics 2013;131(3):e829–36. [DOI] [PubMed] [Google Scholar]
- [19].Davidoff AM, Interiano RB, Wynn L, Delos Santos N, Dome JS, Green DM, et al. Overall Survival and Renal Function of Patients With Synchronous Bilateral Wilms Tumor Undergoing Surgery at a Single Institution. Annals of surgery 2015;262(4):570–6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [20].Interiano RB, Delos Santos N, Huang S, Srivastava DK, Robison LL, Hudson MM, et al. Renal function in survivors of nonsyndromic Wilms tumor treated with unilateral radical nephrectomy. Cancer 2015;121(14):2449–56. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [21].Siemer S, Hack M, Lehmann J, Becker F, Stockle M. Outcome of renal tumors in young adults. J Urol 2006;175(4):1240–3. [DOI] [PubMed] [Google Scholar]
- [22].Thompson RH, Ordonez MA, Iasonos A, Secin FP, Guillonneau B, Russo P, et al. Renal cell carcinoma in young and old patients--is there a difference? J Urol 2008;180(4):1262–6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [23].Thompson RH, Siddiqui S, Lohse CM, Leibovich BC, Russo P, Blute ML. Partial versus radical nephrectomy for 4 to 7 cm renal cortical tumors. J Urol 2009;182(6):2601–6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [24].Estrada CR, Suthar AM, Eaton SH, Cilento BG Jr. Renal cell carcinoma: Children’s Hospital Boston experience. Urology 2005;66(6):1296–300. [DOI] [PubMed] [Google Scholar]
- [25].Shah PH, Moreira DM, Okhunov Z, Patel VR, Chopra S, Razmaria AA, et al. Positive Surgical Margins Increase Risk of Recurrence after Partial Nephrectomy for High Risk Renal Tumors. J Urol 2016;196(2):327–34. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [26].Miller DC, Saigal CS, Banerjee M, Hanley J, Litwin MS, Urologic Diseases in America P. Diffusion of surgical innovation among patients with kidney cancer. Cancer 2008;112(8):1708–17. [DOI] [PMC free article] [PubMed] [Google Scholar]
- [27].Broughton GJ, Clark PE, Barocas DA, Cookson MS, Smith JA Jr., Herrell SD, et al. Tumour size, tumour complexity, and surgical approach are associated with nephrectomy type in small renal cortical tumours treated electively. BJU Int 2012;109(11):1607–13. [DOI] [PubMed] [Google Scholar]
- [28].Vemulakonda VM, Cowan CA, Lendvay TS, Joyner BD, Grady RW. Surgical management of congenital ureteropelvic junction obstruction: a Pediatric Health Information System database study. J Urol 2008;180(4 Suppl):1689–92. [DOI] [PubMed] [Google Scholar]
- [29].Bouty A, Burnand K, Nightingale M, Roberts A, Campbell M, O’Brien M, et al. What is the risk of local recurrence after laparoscopic transperitoneal radical nephrectomy in children with Wilms tumours? Analysis of a local series and review of the literature. J Pediatr Urol 2018;14(4):327 e1–e7. [DOI] [PubMed] [Google Scholar]
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