Second generation of AHOPCA (Asociación de Hemato‐Oncología Pediátrica de Centro América) treatment guidelines for Wilms tumor: A report of outcomes

Background

The AHOPCA (Asociación de Hemato-Oncología Pediátrica de Centro América) Wilms tumor (WT) treatment guidelines, adapted from NWTS-4 and -5 and recommending upfront nephrectomy (UN), were modified to include 4-6 weeks of preoperative chemotherapy (POC) in frail patients with advanced disease. We aim to describe the outcomes of this implemented approach.

Procedure

A retrospective analysis of prospectively collected data from newly diagnosed patients with unilateral WT between 2012 and 2018.

Results

Of 353 eligible patients, 247 (70%) received POC. The POC group had higher initial tumor volume (median 590 mL vs. 308 mL, p < 0.0001) and more Stage IV disease (30% vs. 3%, p < 0.0001) compared to the UN group. During POC, there were 4 deaths, 14 abandonments, and 11 progressive diseases. After response assessment, 62% showed partial tumor response with a median tumor volume reduction to 257 mL. A total of 218 (88.2%) patients underwent nephrectomy. Tumor rupture/spillage occurred in 17.9% of the UN and 18.8% of the POC group; local Stage III was found in 55% of the UN and 68.3% of the POC group. Anaplasia (focal and diffuse) was present in 13.6% (17% UN and 11.9% POC). The 5-year abandonment-sensitive event-free survival (asEFS) and abandonment-sensitive overall survival (asOS) rates were 69% ± 2.5% and 75% ± 2.4%, respectively. The asEFS rates were 75% ± 4.3% for UN and 66% ± 3.0% for POC (p = 0.07).

Conclusions

Many AHOPCA patients presented with unresectable advanced disease, requiring the use of POC. POC effectively reduced tumor volume and facilitated safe surgery in fragile patients. Adopting the standard SIOP WT neoadjuvant approach could enhance staging and risk stratification in AHOPCA.