Global Disparities in Wilms Tumor

Background: Wilms tumor accounts for more than 90% of all malignant kidney neoplasms in children. Survival after diagnosis and treatment is excellent in most high-income countries. Low- and middle-income countries (LMICs) continue to struggle with Wilms tumor detection and treatment. The purpose of this study was to compare the global incidence and outcomes of Wilms tumor.

Material and methods: Wilms tumor incidence data from the World Health Organization (WHO), International Incidence of Childhood Cancer, Volume III, was analyzed according to world region and country socioeconomic status using descriptive statistics and independent-sample Kruskal-Wallis Test. A literature review was also performed to assess outcomes and identify common themes.

Results: Wilms tumor was most common in children aged 0-4 y (median incidence 15.1 [IQR 11.8-18.7] ASR/million). High-income countries reported significantly higher median incidence than middle-income countries (8.6 [7.4-9.3] versus 6.1 [4.9-8.7] ASR/million; P < 0.01), although low-income countries reported the highest median incidence overall (9.8 [6.2-16.4] ASR/million). Low-income countries had the fewest countries with registries (n = 6). Overall survival ranged from 70% to 97% in high-income countries, 61%-94% in upper-middle-income countries, 0%-85% in lower-middle-income countries, and 25%-53% in low-income countries. Delay in diagnosis, lack of available treatment, and inadequate follow up contributed to the large variations in outcomes.

Conclusions: Reported Wilms tumor incidence is highest in low-income countries, and these are also the countries that have the lowest survival. Lack of significance may reflect incomplete and absent data reporting from lower income countries. Accurate and comprehensive registries are the first steps to appropriate resource allocation in order to improve outcomes for this highly curable childhood malignancy.