World Journal of Nephrology and Urology, ISSN 1927-1239 print, 1927-1247 online, Open Access
Article copyright, the authors; Journal compilation copyright, World J Nephrol Urol and Elmer Press Inc
Journal website https://wjnu.elmerpub.com

Original Article

Volume 15, Number 2, April 2026, pages 42-54

Renal Tumors in Young Adults: A Systematic Review and Meta-Analysis of Epidemiology, Clinical Features, Histopathology, and Outcomes Over Two Decades

Figures

↓  Figure 1. PRISMA 2020 flow diagram of study selection. Flow diagram showing identification, screening, eligibility assessment, and inclusion of studies evaluating renal tumors in young adults (18–45 years).
Figure 1.
↓  Figure 2. Forest plot of pooled proportion of incidental tumor diagnosis. Random-effects generalized linear mixed model (GLMM) estimating the pooled proportion of tumors detected incidentally. Proportions are presented with 95% confidence intervals.
Figure 2.
↓  Figure 3. Forest plot of pooled proportion of symptomatic tumor diagnosis. Random-effects GLMM estimating pooled symptomatic presentation rates with 95% confidence intervals.
Figure 3.
↓  Figure 4. Forest plot of pooled mean tumor size (cm). Random-effects inverse-variance model showing pooled mean tumor size with 95% confidence intervals. Heterogeneity assessed using I2 and τ2 statistics.
Figure 4.
↓  Figure 5. Forest plot of pooled proportion of clear cell histology. Random-effects GLMM estimating prevalence of clear cell renal cell carcinoma among young adults.
Figure 5.
↓  Figure 6. Forest plot of pooled proportion of papillary histology. Random-effects GLMM estimating prevalence of papillary renal cell carcinoma.
Figure 6.
↓  Figure 7. Forest plot of pooled proportion of chromophobe histology. Random-effects GLMM estimating prevalence of chromophobe renal cell carcinoma.
Figure 7.
↓  Figure 8. Forest plot of pooled proportion of tumor recurrence. Random-effects GLMM estimating pooled recurrence rate following treatment.
Figure 8.
↓  Figure 9. Forest plot of pooled proportion of overall mortality. Random-effects GLMM estimating pooled mortality rate among included cohorts.
Figure 9.
↓  Figure 10. Funnel plot assessing publication bias for clear cell histology. Funnel plot of standard error versus logit-transformed proportion. Symmetry assessed visually.
Figure 10.
↓  Figure 11. Funnel plot assessing publication bias for papillary histology. Standard error plotted against logit-transformed pooled proportions.
Figure 11.
↓  Figure 12. Funnel plot assessing publication bias for chromophobe histology. Visual assessment of small-study effects.
Figure 12.
↓  Figure 13. Funnel plot assessing publication bias for overall mortality. Standard error plotted against logit-transformed pooled proportions.
Figure 13.

Table

↓  Table 1. Risk of Bias Assessment of Included Studies Using the Newcastle–Ottawa Scale (NOS)
 
StudySelectionComparabilityOutcomeOverall NOS
The figure presents domain-specific star ratings for selection (max 4), comparability (max 2), and outcome (max 3) across 16 studies on renal tumors in young adults. Overall scores range from 0 to 9, with risk of bias categorized as low (7–9 stars), moderate (4–6 stars), or serious (0–3 stars). Higher scores indicate lower risk of bias.
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