Dix DB, et al. - Experts applied a new risk stratification and treatment strategy for Wilms tumor to improve event-free survival (EFS) while reducing exposure to lung radiation therapy (RT). After omission of primary lung RT, excellent overall survival (OS) was achieved in patients with lung nodule CR, yet there were more events than expected. In patients with lung nodule IR using 4 cycles of cyclophosphamide/etoposide in addition to vincristine/dactinomycin/doxorubicin (DD4A), EFS was significantly improved and OS was excellent. EFS and OS estimates were superior to previous studies.

Methods

• Researchers continued chemotherapy without lung RT in patients with favorable histology Wilms tumor and isolated lung metastases showing complete lung nodule response (CR) after 6 weeks of DD4A.
• Lung RT and four cycles of cyclophosphamide/etoposide, in addition to DD4A (Regimen M), was given to patients with incomplete response (IR) or loss of heterozygosity at chromosomes 1p/16q.
• To preserve a 4-year EFS of 85% for lung nodule CR and improve 4-year EFS from 75% to 85% for lung nodule IR, the AREN0533 study was designed.

Results

• As per data, among 292 assessable patients, 133 had CR and 159 had IR.
• Findings suggested that 4-year EFS and OS estimates were 79.5% (95% CI, 71.2% to 87.8%) and 96.1% (95% CI, 92.1% to 100%), respectively for patients with CR.
• The expected vs observed event rates were 15% and 20.2% (P=.052), respectively.
• Four-year EFS and OS estimates for patients with IR were 88.5% (95% CI, 81.8% to 95.3%) and 95.4% (95% CI, 90.9% to 99.8%), respectively.
• The expected vs observed event rates were 25% and 12.2% (P< .001), respectively.
• They found that the overall, 4-year EFS and OS were 85.4% (95% CI, 80.5% to 90.2%) and 95.6% (95% CI, 92.8% to 98.4%) compared with 72.5% (95% CI, 66.9% to 78.1%; P < .001) and 84.0% (95% CI, 79.4% to 88.6%;P < .001), respectively, in the predecessor NWTS-5 study.