Predictors of treatment outcome of Wilms Tumour in low-income country; single centre experience from Pakistan.

BACKGROUND: Wilms tumor (WT) represents around 85% of pediatric renal tumors. In high-income countries, 5-years survival of WT is above 90% but survival in developing countries is inferior. OBJECTIVE: To identify the predictors of treatment outcome of WT in a developing country. METHODS: A retrospective study conducted at the pediatric oncology department, Combined Military Hospital Rawalpindi, Pakistan. All newly diagnosed WT cases from 1st January 2012 who completed their treatment before 31st August 2019 were evaluated. Treatment was based on SIOP Wilms Tumour 2001/UK version 5. Patients presenting before nephrectomy received pre-operative chemotherapy. The postoperative chemotherapy regimen was decided according to the stage, risk stratification and metastatic status of the patient. RESULTS: Data of 84 cases, including 40 (47.6%) males and 44 (52.4%) females was analyzed. The mean diagnostic age was 38.87 ± 28.66 months and 68 (81%) cases were less than five years of age. The commonest presenting features were abdominal mass in 75 (89.3%) cases. The right kidney was affected in 43 (51.2%) cases. Stage I disease was documented in 27 (32.1%) cases, stage II in 25 (29.8%), stage III in 13 (15.5%), and stage IV in 17 (20.2%) cases. In univariate analysis, advanced stage (P = < 0.001) and metastatic disease (P=< 0.001) adversely affected the treatment outcome. Multivariate analysis demonstrated that advanced stage WT was associated with the worst outcome (P= < 0.05). Four (4.8%) cases had treatment-related mortality (TRM). With a median follow-up time of 28.26 ± 23.03 months, OS and EFS were 66 (78.6%) and 63 (75.0%) respectively. DISCUSSION: Delayed presentation with advanced-stage metastatic disease is quite common in the developing courtiers and is the major contributor to decreased EFS and OS. In the present study, 20.2% cases had metastatic disease, which is similar to reported from other developing countries. OS decreased from 92.6% in stage I to 47.1% in stage IV disease (P=< 0.001) and EFS decreased from 92.6% in stage I to 43.8% in stage IV disease (P=< 0.001). Very similar results are reported by a regional study [17]. Results in stage I and II disease are comparable to documented in the western world and inferior in advanced-stage disease. The strength of the present study is that multiple factors, affecting the treatment outcome of WT over almost seven years period were evaluated. CONCLUSIONS: Stage of the disease is the most important prognostic factor. Delayed presentation with metastatic disease has a poor outcome.