Factors influencing clinical response to neoadjuvant therapy among Wilms tumor patients undergoing nephrectomy: a 5-year retrospective cohort study at Muhimbili National Hospital, Tanzania

Background Nephroblastoma, a prevalent pediatric cancer, can be effectively treated using a multimodal approach. Neoadjuvant chemotherapy, a component of this approach, is key in improving surgical and overall outcomes. However, response rates in sub-Saharan Africa are often suboptimal. This study aimed to identify factors influencing the response to neoadjuvant therapy in pediatric patients with Wilms tumor undergoing nephrectomy. Methodology A retrospective cohort study conducted in January 2024 at a quaternary hospital in Tanzania involved 113 pediatric patients with confirmed nephroblastoma who underwent nephrectomy between January 2018 and December 2023. Clinico-demographic, pathological, and therapeutic factors were analyzed using a gamma regression model with a generalized estimating equation to assess their impact on tumor volume changes (pre- vs. post-chemotherapy). Results The median age at diagnosis was 48 months (IQR: 24–60), with a 1:1 male-to-female ratio. Significant tumor volume reduction was noted post-chemotherapy (7125 cm 3 (IQR: 3312–11,884) to 3621 cm 3 (IQR: 1708–7798), p < 0.001), although 63.7% had stable disease (neither sufficient shrinkage to qualify for partial response (PR) nor sufficient increase to qualify for progressive disease (PD), taking as reference the smallest sum longest diameter (LD) since the treatment started). Volume reduction was associated with stage II disease ( β = −0.487, p = 0.023) and a 6-week chemotherapy regimen ( β = −0.946, p = 0.011). Progression correlated with age > 48 months ( β = 0.416, p = 0.020), malnutrition ( β = 0.812, p = 0.023), and prolonged illness ( β = 0.063, p = 0.003). Conclusion Neoadjuvant chemotherapy significantly reduced tumor volume, but stable disease was common. Further research is needed on optimal chemotherapy cycles and the impact of disease stage on treatment response. Prioritizing early diagnosis and tailored treatment for older and malnourished children is crucial in addressing age-related and nutritional challenges affecting therapy effectiveness.