Clinical relevance of mutations in the Wilms tumor suppressor 1 gene <i>WT1</i> and the cadherin‐associated protein β1 gene <i>CTNNB1</i> for patients with Wilms tumors

Abstract BACKGROUND. Mutations in the Wilms tumor (WT) suppressor 1 gene ( WT1 ) and the cadherin‐associated protein β1 gene ( CTNNB1 ) are found predominantly in stromal type WT, defining a genetic subgroup. The clinical relevance of these mutations remains to be determined. METHODS. A long‐term follow‐up study was performed for 71 patients (International Society of Pediatric Oncology Study 9/Society for Pediatric Oncology; n = 77 tumors) with known molecular genetic status. Eight patients had bilateral disease, including 2 patients with a WT in both kidneys and 5 patients with a WT in 1 kidney and nephrogenic rests (NRs) in the other kidney. The response to preoperative chemotherapy, relapses, metastases, metachronous tumor development, and deaths were evaluated with a median follow‐up of 12 years and 4 months. RESULTS. Nineteen patients (n = 24 tumors) had WT1 mutations, and 16 were constitutional mutations. Three patients with germline mutations had second tumor events: Two patients developed a WT in the kidney with NRs 3 years and 11 years after the first tumor; and 1 patient developed second tumors after 2 years, 1 in the kidney with a previous WT and 1 in the kidney with a previous NR. Eighteen of the WT1 mutant tumors were analyzed for CTNNB1 mutations, and all had mutations. A poor volumetric response (progression and &lt;50% reduction) was observed in all patients who had tumors with a WT1 mutation and in 23 of 52 nonmutant tumors. CONCLUSIONS. Patients with WT1 germline mutations had an increased risk for bilateral disease and second tumor events. Therefore, the authors concluded that tumor surveillance until adulthood should be considered. Although tumors with both WT1 and CTNNB1 mutations had a poor volumetric response, there was no significant difference in overall survival in this cohort of patients with and without WT1 mutations. Cancer 2008. © 2008 American Cancer Society.