Outcome of Wilms tumor patients with bone metastasis enrolled on National Wilms Tumor Studies 1-5: A report from the Children's Oncology Group

Background Wilms tumor (WT) is the most common renal tumor in children. We describe the outcomes for patients with WT that metastasized to bone (WTBM) to assist in decision making for these uncommon patients. Procedure Results We retrospectively reviewed the research records of patients identified with WTBM from the National Wilms Tumor Study (NWTS 1-5) database. We then related overall survival (OS) to histology, chemotherapy, radiation therapy to bone, location of metastasis, and when bone metastasis presented. Thirty-eight of 8609 patients enrolled on NWTS 1-5 (0.44%) developed bone metastasis. Bone metastasis most commonly first occurred at progression or relapse (29/38, 76%). Five of thirty-eight survived (13%) with the 5-year OS following presentation of bone metastasis of 14.3% (95% CI: 2.7-25.8%). The primary cause of death was tumor (29/33, 88%). Of those who died, the median survival time was 10.9 months (range 0.49-61.4). Four of nine (44%) patients presenting at diagnosis and 3% (1/29) of patients presenting in progression or relapse survived (P = 0.0075). Nineteen percent (5/26) of patients with favorable histology and 0% (0/12) with anaplastic histology survived (P = 0.16). Of the five survivors, median follow-up was 14 years (range 6.7-23.8). Radiation to metastatic bone sites was recorded in three of five survivors. No consistent chemotherapeutic approach appeared to be associated with disease outcome. Conclusion Bone metastasis is rare in patients with WT, occurring more commonly in progression or relapse than at initial diagnosis. Patients with WTBM have poor prognosis. We could not identify a consistent chemotherapeutic strategy associated with survival.