Objective: To evaluate age, TNW, or tumor diameter (TD) as continuous prognostic variables for outcomes in early stage FHWT after accounting for biology and treatment.
Summary of background data: Patient age (< 2 vs. ≥ 2 years) and tumor nephrectomy weight (TNW; < 550g vs. ≥ 550 grams) have been used to risk stratify children with stage I favorable histology Wilms tumor (FHWT) on Children's Oncology Group (COG) studies and select patients for omission of chemotherapy.
Methods: Included patients had stage I or II FHWT per central review and were treated with nephrectomy only, EE4A, or DD4A on COG trials. Restricted cubic splines models were used to estimate the stage-specific effects of age, TNW, and TD on event-free survival (EFS) and overall survival (OS), accounting for treatment and biology.
Results: In pooled analyses of 775 stage I and 936 stage II patients, age was not significantly associated with EFS or OS for stage I or II patients after accounting for adverse biology that is more prevalent with older age. Greater TNW and larger TD were associated with increased risk of relapse in stage I and increased risk of death in stage II, but not when restricted to patients less than 4 years old.
Conclusions: Age, TNW, and TD are each prognostic for EFS or OS in some cohorts of patients with stage I or II FHWT. However, after accounting for adverse biology that becomes more prevalent at older ages, these factors are no longer independently prognostic. The next COG FHWT study will implement and validate these findings.
Keywords: age, tumor nephrectomy weight; favorable histology Wilms tumor; prognostic factors; tumor diameter.
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