Predictors of Surgical Complications and Survival in Pediatric Wilms' Tumor: A 20-Year Retrospective Study from Two Thai Centers.

(1) Background: Wilms' tumor (WT) is the most common pediatric renal malignancy. Although survival outcomes have improved with multimodal therapy, the optimal sequence of surgery and chemotherapy remains debated, particularly in resource-limited settings. This study evaluates the effect of treatment strategy on surgical complications and survival, utilizing two decades of data from Thai tertiary centers. (2) Methods: A retrospective cohort study was conducted on 83 children who underwent radical nephrectomy for WT between 2002 and 2022 at two university hospitals in Thailand. Patients were grouped by treatment protocol: primary nephrectomy (n = 59) or neoadjuvant chemotherapy (n = 24). Clinical, pathological, operative, and follow-up data were analyzed to identify predictors of surgical complications and survival. (3) Results: Short-term postoperative complications occurred in 16.9% of cases, more frequently in males and in patients with hypoalbuminemia, anemia, or large tumors. Estimated blood loss greater than 5 mL/kg, serum albumin less than 3.5 g/dL, and hemoglobin lower than 10 g/dL were independent predictors of complications. The five-year overall survival (OS) and progression-free survival (PFS) rates were 82.4% and 68.1%, respectively. Patients with unfavorable histology or short-term complications experienced significantly poorer OS. Neoadjuvant chemotherapy was associated with increased nutritional compromise and a trend toward higher complication rates, although it was not directly linked to inferior OS. (4) Conclusions: In pediatric WT, the perioperative nutritional and hematologic statuses significantly influence surgical outcomes. While neoadjuvant chemotherapy may assist in tumor downsizing, it might also compromise surgical fitness. Customized preoperative risk assessment and nutritional support can enhance outcomes, particularly in low- and middle-income countries.