Characteristics and outcomes of preoperatively treated patients with anaplastic Wilms tumors registered in the UK SIOP-WT-2001 and IMPORT study cohorts (2002-2020)

Bilateral Wilms tumor with anaplasia: A report from the Children's Oncology Group Study AREN0534

INTRODUCTION

The purpose of this study is to examine the outcomes in children with anaplastic bilateral Wilms tumor (BWT) from study AREN0534 in order to define potential prognostic factors and areas to target in future clinical trials.

METHODS

Demographic and clinical data from AREN0534 study patients with anaplasia (focal anaplasia [FA], or diffuse anaplasia [DA]) were compared. Event-free survival (EFS) and overall survival (OS) were reported using Kaplan-Meier estimation with 95% confidence bands, and differences in outcomes between FA and DA compared using log-rank tests. The impact of margin status was analyzed.

RESULTS

Twenty-seven children who enrolled on AREN0534 had evidence of anaplasia (17 DA, 10 FA) in at least one kidney and were included in this analysis. Twenty-six (96%) had BWT. Nineteen percent had anaplastic histology in both kidneys (four of 17 DA, and one of 10 FA). Forty-six percent with BWT had bilateral nephron-sparing surgery (NSS); one child who went off protocol therapy, eventually required bilateral completion nephrectomies. Median follow-up for EFS and OS was 8.6 and 8.7 years from enrollment. Four- and 8-year EFS was 53% [95% confidence interval (CI): 34%-83%] for DA; 4-year EFS was 80% [95% CI: 59%-100%], and 8-year EFS 70% [95% CI: 47%-100%] for FA. Three out of 10 children with FA and eight out of 17 children with DA had events. EFS did not differ statistically by margin status (p = .79; HR = 0.88). Among the six children who died (five DA, one FA), all experienced prior relapse or progression within 18 months.

CONCLUSION

Events in children with DA/FA in the setting of BWT occurred early. Caution should be taken about interpreting the impact of margin status outcomes in the context of contemporary multimodal therapy. Future targeted investigations in children with BWT and DA/FA are needed.

Anaplasia in Wilms tumor: A critical review

Anaplasia in Wilms tumor is recognized as the most important prognostically unfavorable histological feature. It is subtyped as focal anaplastic Wilms tumor (FAWT) and diffuse anaplastic Wilms tumor (DAWT). Outcomes of patients with DAWT remain poor in patients with stage III and IV tumors. Important issues relevant to anaplasia in Wilms tumor, including prevalence, treatment, outcomes, biomarkers, anaplasia, and chemotherapy, and the concept of tumor aggressiveness, are reviewed and discussed here. We also consider the differences in clinical approaches to anaplasia in Wilms tumor between the two major renal tumor clinical research groups: the International Society of Paediatric Oncology (SIOP) Renal Tumour Study Group and the Children's Oncology Group (COG) Renal Tumor Group. We emphasize the importance and implications of recognizing FAWT and DAWT as separate clinico-pathological entities.

Incidence and survival for childhood cancer by endorsed non-stage prognostic indicators in Australia

BACKGROUND

An international expert panel recently recommended 15 'non-stage prognostic indicators' (NSPIs) across eight childhood cancers, classified as essential or additional, for collection in population-based cancer registries. We aimed to describe the incidence distribution and survival of each of these NSPIs.

PROCEDURES

Cases were extracted from the Australian Childhood Cancer Registry. The study cohort (n = 4187) comprised all children aged under 15 years diagnosed with an eligible cancer between 2010 and 2018, with follow-up until 31 December 2020. NSPI data were collected directly from each patient's medical records. Differences in 5-year relative survival were assessed using multivariable flexible parametric models, adjusted for sex and age group at diagnosis.

RESULTS

The availability of data varied, exceeding 85% for all essential NSPIs apart from histologic subtype for Wilms tumours (69%) and lineage for acute lymphoblastic leukaemia (78%). Information on additional NSPIs tended to be recorded less often, particularly cytogenetic subtype for non-alveolar rhabdomyosarcoma (28%) and astrocytoma (4%). Eight NSPIs exhibited a significant difference in survival, with the largest disparity occurring among children with astrocytoma according to tumour grade (5-year relative survival of 18% for grade IV disease compared with 99% for grade I disease; p < .001).

CONCLUSIONS

Our findings demonstrate that most of the recommended NSPIs can be retrieved from medical records in Australia in recent years, allowing the capability of assessing survival within patient subgroups of clinical interest. Reporting of NSPI data has the capability to inform local and global understanding of population-level disparities in childhood cancer survival.

Hepatic Metastasectomy in Pediatric Patients: An Observational Study

BACKGROUND

The role of hepatectomy for metastatic disease in children is controversial. Rationales include potential cure, obtaining a diagnosis, and guiding chemotherapy decisions. This study examines the safety and utility of hepatic metastasectomy for children at a single institution.

METHODS

After IRB approval (#22-1258), medical records were reviewed from 1995 to 2022 for children undergoing hepatic metastasectomy. En-bloc hepatectomies during primary tumor resection were excluded.

RESULTS

Hepatic metastasectomy was performed in 16 patients for a variety of histologies. Median patient age was 12.2 years [IQR 6.9-22.6], and 13/16 patients were female (81 %). Number of hepatic metastases ranged from 1 to 23 and involved between 1 and 8 Couinaud segments. Anatomic resections included 4 hemihepatectomies and 1 sectionectomy. All other resections were nonanatomic. 3/6 resections for germ cell tumor (GCT) revealed only mature teratoma, driving adjuvant therapy decisions. When indicated, median time to adjuvant chemotherapy was 19 days [IQR 11-22]. No patients had Clavien-Dindo Class III or higher perioperative morbidity. Three patients (1 GCT, 1 adrenocortical carcinoma (ACC), and 1 gastric neuroendocrine tumor (GNET) experienced hepatic relapse. The patients with relapsed GCT and GNET are alive with disease at 17 and 135 months, respectively. The patient with ACC died of disease progression and liver failure. One patient with Wilms tumor experienced extrahepatic, retroperitoneal recurrence and died. With a median follow-up of 38 months, 10-year disease-specific and disease-free survival were 77 % and 61 %, respectively.

CONCLUSIONS

Hepatic metastasectomy can be accomplished safely in children, may guide adjuvant therapy decisions, and is associated with long-term survival in selected patients.

LEVEL OF EVIDENCE

Level IV.

TYPE OF STUDY

Treatment Study, Case series with no comparison group.

A Gradual Transition Toward Anaplasia in Wilms Tumor Through Tolerance to Genetic Damage

Patients with Wilms tumor (WT) in general have excellent survival, but the prognosis of patients belonging to the subgroup of WT with diffuse anaplasia (DA) is poor due to frequent resistance to chemotherapy. We hypothesized that DA WT cells might undergo changes, such as acquiring a persistent tolerance to DNA damage and copy number aberrations (CNAs), which could eventually lead to their resistance to chemotherapy treatment. Tissue sections from chemotherapy-treated DA WTs (n = 12) were compared with chemotherapy-treated nonanaplastic WTs (n = 15) in a tissue microarray system, enabling analysis of 769 tumor regions. All regions were scored for anaplastic features and immunohistochemistry was used to quantify p53 expression, proliferation index (Ki67), and DNA double-strand breaks (γH2AX). CNAs were assessed by array-based genotyping and TP53 mutations using targeted sequencing. Proliferation index and the frequency of DNA double-strand breaks (γH2AX dot expression) increased with higher anaplasia scores. Almost all (95.6%) areas with full-scale anaplasia had TP53 mutations or loss of heterozygosity, along with an increased amount of CNAs. Interestingly, areas with wild-type TP53 with loss of heterozygosity and only one feature of anaplasia (anaplasia score 1) also had significantly higher proliferation indices, more DNA double-strand breaks, and more CNAs than regions without any anaplastic features (score 0); such areas may be preanaplastic cell populations under selective pressure for TP53 mutations. In conclusion, we suggest that chemoresistance of DA WTs may be partly explained by a high proliferative capability of anaplastic cells, which also have a high burden of double-stranded DNA breaks and CNAs, and that there is a gradual emergence of anaplasia in WT.

Stage I epithelial or stromal type Wilms tumors are low risk tumors: An analysis of patients treated on the SIOP-WT-2001 protocol in the UK-CCLG and GPOH studies (2001-2020)

BACKGROUND

Patients treated with preoperative chemotherapy with stage I intermediate-risk Wilms tumor (IR-WT) represent the largest group of patients with Wilms tumor (WT), and they have excellent outcomes.

METHODS

The authors performed a retrospective analysis of patients with stage I epithelial (ET-WT) or stromal type WT (ST-WT) treated pre- and postoperatively according to the International Society of Paediatric Oncology-WT-2001 protocol in the UK Children's Cancer and Leukaemia Group and Gesellschaft für Pädiatrische Onkologie und Hämatologie groups' participation in the relevant WT trials and studies (2001-2020).

RESULTS

There were 880 patients with stage I IR-WT, including 124 with ET-WT, 156 with ST-WT, and 600 with other IR-WT (oIR-WT). Patients with stage I ET-WT or ST-WT were significantly younger than patients with oIR-WT, represented a large proportion of stage I WTs in their groups, and tumors showed poor histologic response to preoperative chemotherapy. The 5-year event-free survival (EFS) estimates for patients with stage I ET-WT (96.8% ± 1.8 SE) or ST-WT (96.8% ± 1.6 SE) were significantly better than for patients with oIR-WT (90.3% ± 1.3 SE) (p = .014 and p = .009, respectively). A multivariate analysis showed that histologic type (ET-WT or ST-WT) remained a significant factor for EFS when adjusted for age and gender (p = .032 and p = .022, respectively). In both groups, relapses occurred in 3.2% of patients, and the overall survival was 99.2%.

CONCLUSIONS

The results suggest that stage I ET-WT or ST-WT could be regarded as low-risk WT, for which omission of postoperative chemotherapy should be considered.

PLAIN LANGUAGE SUMMARY

Patients with pretreated intermediate-risk Wilms tumor (WT) represent the largest group of patients with WT. This study reports the outcomes of patients with stage I epithelial type (ET-WT) or stromal type WT (ST-WT). These patients were significantly younger and had a larger proportion of stage I cases than patients with other intermediate-risk WT (oIR-WT). The event-free survival for patients with stage I ET-WT and ST-WT was significantly better than for patients with oIR-WT. Rare relapses were curable resulting in 99.2% overall survival.