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Whereas 90% of patients with Wilms tumor (WT) reach cure, approximately half of patients developing a recurrent tumor die of the disease. Therefore, to disclose events leading to recurrence represents a clinical need. To study paired primary/recurrent tumor samples, being aware of the intra-tumoral heterogeneity, might help finding these answers. We previously suggested that mutations in SIX1 and DROSHA underlie WT recurrence. With the aim to better investigate this scenario, we collected 19 paired primary/recurrent tumors and 10 primary tumors from relapsing patients and searched for mutations in the SIX1/2 genes and microRNA processing genes (miRNAPGs). We found SIX1 mutation in one case, miRNAPGs mutations in seven cases, and the co-occurrence of SIX1 and miRNAPG mutations in one case. We could observe that, whereas in primary tumors the mutations could be heterogeneously present, in all cases they were positively selected and homogeneously present in the recurrent disease, as also indicated by a “moderate” and “almost perfect” agreement (according to the Landis and Koch classification criteria) between paired samples. Analysis of SIX1/2 genes and miRNAPGs in 50 non-relapsing WTs disclosed SIX2 mutation in one case and miRNAPGs mutations in seven. A borderline statistically significant association was observed between miRNAPGs mutations and the occurrence of relapse (p value: 0.05). These data suggest that SIX1 and miRNAPGs mutations may provide an advantage during tumor progression to recurrence and can represent oncogenic drivers in WT development.

TW2003, the third Italian prospective study on Wilms tumor, aimed to improve survival in patients with stage III-IV tumors, de-escalate therapy for stage I-II nonanaplastic tumors, refine the risk stratification of therapy, and develop a national infrastructure for biobanking and central pathology review.TW2003 recruited children 18 years old or younger with primary intrarenal tumors. Local physicians chose nephrectomy with or without preoperative chemotherapy as the initial treatment based on the risk of unsafe and/or incomplete immediate surgery. The main drivers for adjuvant therapy were tumor stage and diffuse anaplasia. A new risk stratification schema was investigated, incorporating patient age, reason for stage III designation and completeness of lung nodule response in stage IV disease.We report on 453 patients with unilateral Wilms tumor. Preoperative chemotherapy was administered to 42% of patients. The 5-year event-free survival and overall survival rates were 89.1% (95% CI 83.6-94.9) and 97.0% (93.7-100) for stage I; 85.1% (79.6-91.1) and 94.0% (90.1-98.1) for stage II (160); 82.7% (75.3-90.8) and 90.9% (85.0-97.1) for stage III (101); and 72.1% (61.9-84.0) and 82.5% (73.1-93.1) for stage IV (69), respectively. On multivariable analysis only anaplasia was significant for event-free survival (HR 2.68, 95% CI 1.48-4.86, p=0.001; bias corrected c-index 0.580) and overall survival (HR 5.29, 95% CI 2.52-11.12, p0.001; bias corrected c-index 0.697).The survival rates achieved and the proposed risk stratification schema provide a basis for future comparisons of Wilms tumor treatment burden and patient outcome.

Background Children with Wilms’ tumor (WT) aged under 24 months (infants) have a better prognosis than older patients. Our aim was to study the epidemiology of this age group, with focus on the modality of diagnosis, tumor size, and association with malformations/syndromes, seeking to understand if any of these factors might be related to prognosis. Patients and methods Infants diagnosed with WT between 2003 and February 2010 were evaluated. A query form was used to collect data on the modality of WT diagnosis (symptomatic or incidental), tumor volume, maximum diameter, site, and stage. Results Data were collected for 117 of 124 WT infants registered. Twenty-four cases had an incidental diagnosis (ID) of renal mass, usually arising from an abdominal ultrasound performed for other reasons, and 93 had been diagnosed based on clinical signs/symptoms. The incidental cohort displayed unifocal disease, mean tumor diameter 5.52 cm, mean tumor volume 84.30 ml, and 14 patients showed associated malformations. Symptomatic patients had mean maximum tumor diameter of 10.18 cm, mean tumor volume of 451.18 ml, and six had associated malformations. Conclusions Our study showed that 20% of the infants had an ID of WT; they had a relatively smaller nonmetastatic tumor and a higher rate of malformations than infants of the symptomatically diagnosed group, but we did not detect any difference in age at diagnosis between the two groups. Conversely, we found a significant difference in the 5-year event-free survival rate (P = 0.018) between infants under 1 year (96%), more frequently associated with congenital malformations, and infants 1–2 years (80%).

Despite the excellent survival rate of Wilms tumor (WT) patients, only approximately one-half of children who suffer tumor recurrence reach second durable remission. This underlines the need for novel markers to optimize initial treatment. We investigated 77 tumors using Illumina 370CNV-QUAD genotyping BeadChip arrays and compared their genomic profiles to detect copy number (CN) abnormalities and allelic ratio anomalies associated with the following clinicopathological variables: relapse (yes vs. no), age at diagnosis (≤24 months vs. >24 months), and disease stage (low stage, I and II, vs. high stage, III and IV). We found that CN gains at chromosome region 1q21.1-q31.3 were significantly associated with relapse. Additional genetic events, including allelic imbalances at chromosome arms 1p, 1q, 3p, 3q, and 14q were also found to occur at higher frequency in relapsing tumors. Interestingly, allelic imbalances at 1p and 14q also showed a borderline association with higher tumor stages. No genetic events were found to be associated with age at diagnosis. This is the first genome wide analysis with single nucleotide polymorphism (SNP) arrays specifically investigating the role of genetic anomalies in predicting WT relapse on cases prospectively enrolled in the same clinical trial. Our study, besides confirming the role of 1q gains, identified a number of additional candidate genetic markers, warranting further molecular investigations. © 2012 Wiley Periodicals, Inc.

Wilms tumour (WT), the most frequent malignant childhood renal tumour, shows a high degree of genetic and epigenetic heterogeneity. Loss of imprinting on chromosome 11p15 is found in a large fraction of cases and mutations in a few genes, including WT1, CTNNB1, WTX, TP53 and, more recently, SIX1, SIX2 and micro RNA processing genes (miRNAPGs), have been observed. However, these alterations are not sufficient to describe the entire spectrum of genetic defects underlying WT development. We inspected data obtained from a previously performed genome-wide single nucleotide polymorphism (SNP) array analysis on 96 WT samples. By selecting focal regions commonly involved in chromosomal anomalies, we identified genes with a possible role in WT development, based on the prior knowledge of their biological relevance, including MYCN, DIS3L2, MIR562, HACE1, GLI3, CDKN2A and CDKN2B, PALB2, and CHEK2. The MYCN hotspot mutation c.131C>T was detected in seven cases (7.3%). Full sequencing of the remaining genes disclosed 16 rare missense variants and a splicing mutation. Most of these were present at the germline level. Promoter analysis of HACE1, CDKN2A and CDKN2B disclosed partial methylation affecting HACE1 in a consistent fraction of cases (85%). Interestingly, of the four missense variants identified in CHEK2, three were predicted to be deleterious by in silico analyses, while an additional variant was observed to alter mRNA splicing, generating a functionally defective protein. Our study adds additional information on putative WT genes, and adds evidences involving CHEK2 in WT susceptibility.