Approximately 15% of patients with favorable histology Wilms tumor and 50% of patients with anaplastic Wilms tumor experience recurrence. Historically, the salvage rate for patients with recurrent favorable histology Wilms tumor was 25% to 40%. As a result of modern treatment combinations, the outcome after recurrence has increased up to 60%.[2,3] A number of potential prognostic features influencing outcome post-recurrence have been analyzed, but it is difficult to separate whether these factors are independent of each other. In addition, the following prognostic factors appear to be changing over time as therapy for primary and recurrent Wilms tumor evolves:
Gender: Gender was predictive of outcome, with males faring worse than females.[2,5]
NWTS-5 showed that time to recurrence and site of recurrence were no longer prognostically significant.[2,5] However, patients who experienced a pulmonary relapse within 12 months of diagnosis had a poorer prognosis (5-year OS, 47%) than did patients who experienced a pulmonary relapse 12 months or more after diagnosis (5-year OS, 75%).
Therapy with neoadjuvant imatinib is under evaluation. It may be used for patients with very large primary gastrointestinal stromal tumors (GIST) or poorly positioned small GIST (considered unresectable without the risk of unacceptable morbidity or functional deficit) until surgical therapy is feasible, which can take as long as 6 to 12 months.[1,2] There are no controlled trials addressing the benefits of imatinib in this setting, so the impact of neoadjuvant imatinib on overall survival (OS) is...
Based on the above, the following three risk categories have been identified:
Standard risk: Patients with favorable histology Wilms tumor with relapse after therapy with only vincristine and/or dactinomycin. These patients are expected to have an event-free survival (EFS) of 70% to 80%. These patients make up approximately 30% of recurrences.
High risk: Patients with favorable histology Wilms tumor with relapse after therapy with three or more agents. These patients account for 45% to 50% of children with Wilms tumor who relapse and have survival rates in the 40% to 50% range.
Very high risk: Patients with recurrent anaplastic or blastemal-predominant Wilms tumor. These patients are expected to have survival rates in the 10% range and they make up 10% to 15% of all Wilms tumor relapses.[3,7]
Treatment of Standard-Risk Relapsed Wilms Tumor
In children who had small, stage I Wilms tumor and were treated with surgery alone, the EFS was 84%. All but one child who relapsed was salvaged with treatment tailored to the site of recurrence. Wilms tumor patients whose initial therapy consisted of immediate nephrectomy followed by chemotherapy with vincristine and dactinomycin who relapse can be successfully retreated. Fifty-eight patients were treated on the National Wilms Tumor Study-5 (COG-Q9401) relapse protocol with surgical excision when feasible, radiation therapy, and alternating courses of vincristine, doxorubicin and cyclophosphamide, and etoposide and cyclophosphamide. Four-year EFS after relapse was 71% and overall survival (OS) was 82%. For patients whose site of relapse was only the lungs, the 4-year EFS rate was 68% and OS rate was 81%.