Outcomes and Predictors of Survival among Children with Wilms Tumor At Uganda Cancer Institute

Abstract

Background: Wilms Tumor (WT) is the most common primary renal tumor of childhood worldwide. It’s one of the successes of pediatric oncology with long term survival above 90% for localized disease and 75% for metastatic disease in high income countries. Despite the high global success rate, overall survival in Sub-Saharan Africa (SSA) averages at 39%. In the last 10 years, the Uganda Cancer Institute (UCI) has improved diagnosis, treatment and follow up of children with Wilms Tumor but has not evaluated treatment outcomes or prognostic predictors to improve outcomes in line with target set by WHO 2030 global initiative for children’s cancer (GICC).General Objective: To determine the outcomes and predictors of survival among children with Wilms tumor at the UCI in the setting of improved care. Methods: A retrospective chart review of children with a histological diagnosis of Wilms tumor between January 2014 and December 2019 was conducted. Clinical and management data were abstracted and analyzed. Kaplan –Meier survival curves and Cox regression models were used to determine the overall survival rates and predictors of survival respectively. Results: Of the 115 children included the mean age at presentation was 3.6 years (2.5),53.9% were females and 65.2% had hypertension. Majority of patients presented with stage III (63%) and stage IV disease (37%) and 40.9% had anaplastic histology. The overall survival rates (OS) of children at one year, three years, and five years were 77.8%, 58.0%, and 48.3% respectively. The medium survival time for the whole cohort was 4.7 years (04014-0.6403). On multivariate cox regression analysis, having both liver and lung metastases [HR = 3.02, P=0.041], focal anaplasia [HR=2.83, P=0.038], diffuse anaplasia [HR =3.08, P=0.005], access to surgery [HR=0.31, P=0.005] and radiotherapy [HR = 0.17, P<0.001] were the predictors of survival. The treatment abandonment rate was 29.6% and 16.5% were lost to follow up. Conclusion and recommendation: Children with Wilms tumor at the UCI have increased rates of hypertension and anaplastic histology. The overall survival rates are higher than most Sub Saharan Africa countries but is lower than what has been seen in high income countries and dose not reach WHO 2030 GICC targets. Anaplastic histology and having both liver and lung metastases are negative predictors of survival while surgery and radiotherapy are positive predictors of survival. Local therapies are paramount for survival but should be more xii accessible. A Wilms tumor registry, local tumor biology studies and prevention of treatment abandonment strategies are targets for improved outcomes. Key words: Wilms tumor, overall survival rate, predictors of survival.