The effect of preoperative chemotherapy on histological subtyping and staging of Wilms tumors: The United Kingdom Children's Cancer Study Group (UKCCSG) Wilms tumor trial 3 (UKW3) experience

Bilateral Peters' anomaly, aniridia and Wilms tumour (WAGR syndrome) in monozygotic twins

AIM

This study reports the bilateral association of Peters' anomaly and congenital aniridia in monozygotic twins subsequently diagnosed with Wilms tumour (WAGR syndrome).

METHODS

Two monozygotic female twins were referred at age 2 months with bilateral corneal opacity. A diagnosis of Peters' anomaly associated to aniridia was made in both eyes of both twins. Physical examination and ultrasonography were carried out at 12 months of age to explore the possibility of WAGR-related anomalies, specifically Wilms tumour. DNA were isolated and subjected to whole exome sequencing.

RESULTS

Peters' anomaly associated to aniridia in both eyes as well as bilateral Wilms tumour in both children were diagnosed. Exome analyses showed a large heterozygous deletion encompassing 6 648 473 bp in chromosome 11p13, using Integrative Genomics Viewer and AnnotSV software.

CONCLUSION

WAGR syndrome is a rare contiguous gene deletion syndrome with a greater risk of developing Wilms tumour associated with Peters' anomaly and congenital aniridia. However, co-occurrence of both anomalies was rarely reported in twins, and never in both eyes of monozygotic twins. Here, we report the bilateral association of Peters' anomaly and congenital aniridia in monozygotic twins with WAGR syndrome.

High Expression of WT1 and Low Expression of p53 in Archived Blocks of Children with Wilms Tumor in South Western Uganda

Purpose

The determination of the presence or absence of anaplasia in Wilms tumor is difficult sometimes creating diagnostic errors and is worsened by the use of neoadjuvant chemotherapy, which causes cellular alterations that may mimic anaplasia. This study described the histological features of Wilms tumor and their association with WT1 and p53 expression in archived specimens in South Western Uganda.

Patients and Methods

A series of 308 formalin-fixed paraffin-embedded tissue blocks belonging to 85 children were retrospectively recruited in the only public Histopathology laboratory in South Western Uganda. Rabbit monoclonal Anti-Wilms tumor protein antibody [(CAN-R9) IHC-56-2] ab89901 and rabbit monoclonal Anti-p53 antibody [E26] ab32389 were used to assess the expression of WT1 and p53, respectively. The expression of WT1 and p53 were reported as proportions, Chi-square was also performed to assess for associations and statistical significance was considered when the p-value was less than 0.05.

Results

The median age was 3.5 with an interquartile range of (2-6) years. Mixed histology was the most common at 35.29% (95% CI:25.77-46.14). Anaplasia was present in 5.88% (95% CI:2.44-13.52) of the specimens. p53 and WT1 expressions were 13.0% (95% CI:7.25-22.04), and 41.0% (95% CI: 31.11-52.04), respectively.

Conclusion

Mixed-type histology is the most common histologic feature of Wilms tumor with high expression of WT1 and a low expression of p53 implying that these can be used routinely to confirm the diagnosis as well as anaplasia in South Western Uganda.

Evidence-based surgical guidelines for treating children with Wilms tumor in low-resource settings

BACKGROUND

Survival of Wilms tumor (WT) is > 90% in high-resource settings but < 30% in low-resource settings. Adapting a standardized surgical approach to WT is challenging in low-resource settings, but a local control strategy is crucial to improving outcomes.

OBJECTIVE

Provide resource-sensitive recommendations for the surgical management of WT.

METHODS

We performed a systematic review of PubMed and EMBASE through July 7, 2020, and used the GRADE approach to assess evidence and recommendations.

RECOMMENDATIONS

Initiation of treatment should be expedited, and surgery should be done in a high-volume setting. Cross-sectional imaging should be done to optimize preoperative planning. For patients with typical clinical features of WT, biopsy should not be done before chemotherapy, and neoadjuvant chemotherapy should precede surgical resection. Also, resection should include a large transperitoneal laparotomy, adequate lymph node sampling, and documentation of staging findings. For WT with tumor thrombus in the inferior vena cava, neoadjuvant chemotherapy should be given before en bloc resection of the tumor and thrombus and evaluation for viable tumor thrombus. For those with bilateral WT, neoadjuvant chemotherapy should be given for 6-12 weeks. Neither routine use of complex hilar control techniques during nephron-sparing surgery nor nephron-sparing resection for unilateral WT with a normal contralateral kidney is recommended. When indicated, postoperative radiotherapy should be administered within 14 days of surgery. Post-chemotherapy pulmonary oligometastasis should be resected when feasible, if local protocols allow omission of whole-lung irradiation in patients with nonanaplastic histology stage IV WT with pulmonary metastasis without evidence of extrapulmonary metastasis.

CONCLUSION

We provide evidence-based recommendations for the surgical management of WT, considering the benefits/risks associated with limited-resource settings.

Pathology of Wilms' tumour in International Society of Paediatric Oncology (SIOP) and Children's Oncology Group (COG) renal tumour studies: similarities and differences

Excellent outcomes for patients with Wilms' tumour (WT), over 90% for all stages together, have been achieved through researching WT in multicentre and multinational trials and studies in the last 50 years, led by two major groups - International Society of Paediatric Oncology (SIOP) and Children's Oncology Group (COG, previously National Wilms' Tumor Study Group). Despite having different approaches, the survival outcomes in two groups are remarkably similar. In general, in SIOP, which is followed in Europe and most other countries around the world, patients are first treated with pre-operative chemotherapy, followed by surgery and, if necessary, post-operative chemotherapy and radiotherapy. In COG, which is mainly followed in North America, patients are treated with upfront surgery, followed, if necessary, by post-operative chemotherapy and radiotherapy. In both groups, post-operative treatment primarily depends on tumour histological classification and stage, although in recent studies, other prognostic factors have been included, too (tumour volume, response to preoperative chemotherapy, molecular markers). Due to separate initial treatments, there are differences in histological assessment and subtyping of WT, and, more importantly, in staging criteria. In this review, we discuss the similarities and differences between the two groups in order to help pathologists who are dealing with WT to understand and follow the pathological protocol which is appropriate for a particular case since in many centres both approaches may be followed depending on individual case's / patient's circumstances.

Renal tumours of childhood: A review

Renal tumours of childhood are rare, although they are one of the most common solid tumours in children. They include numerous entities, which have different clinical, histological, molecular biological and prognostic features, so their precise diagnosis and staging are critical for appropriate treatment. The most common is Wilms' tumour (WT) with ~80-85 % of all cases, whereas other entities including mesoblastic nephroma, clear cell sarcoma, rhabdoid tumour, renal cell carcinoma, metanephric tumours and others are very rare (2-4 % each) which explains why they represent a big diagnostic challenge for diagnostic pathologists. They are subclassified into three risk groups - low, intermediate and high - which have different treatments and prognosis. There are two big study groups which have different approaches but remarkable similar outcomes. The International Society of Paediatric Oncology approach (followed in most of the world) is based on preoperative chemotherapy, followed by surgery and further therapy, whereas the Children's Oncology Group approach (followed mainly in the United States and Canada) is based on primary surgery, followed by postoperative treatment.

Prognostic significance of histopathological response to preoperative chemotherapy in unilateral Wilms' tumor: An analysis of 899 patients treated on the SIOP WT 2001 protocol in the UK-CCLG and GPOH studies

In the SIOP Wilms' tumor (WT) studies, preoperative chemotherapy is used as primary treatment, and tumors are classified thereafter by pathologists. Completely necrotic WTs (CN-WTs) are classified as low-risk tumors. The aim of the study was to evaluate whether a subset of regressive type WTs (RT-WTs) (67%-99% chemotherapy-induced changes [CIC]) showing an exceptionally good response to preoperative chemotherapy had comparably excellent survivals as CN-WTs, and to establish a cut-off point of CIC that could define this subset. The study included 2117 patients with unilateral, nonanaplastic WTs from the UK-CCLG and GPOH-WT studies (2001-2020) treated according to the SIOP-WT-2001 protocol. There were 126 patients with CN-WTs and 773 with RT-WTs, stages I-IV. RT-WTs were subdivided into subtotally necrotic WTs (>95% CIC) (STN-WT96-99) (124 patients) and the remaining of RT-WT (RR-WT67-95) (649 patients). The 5-year event-free survival (EFS) and overall survival (OS) for CN-WTs were 95.3% (±2.1% SE) and 97.3% (±1.5% SE), and for RT-WTs 85.7% (±1.14% SE, P < .01) and 95.2% (±0.01% SE, P = .59), respectively. CN-WT and STN-WT96-99 groups showed significantly better EFS than RR-WT67-95 (P = .003 and P = .02, respectively), which remained significantly superior when adjusted for age, local stage and metastasis at diagnosis, in multivariate analysis, whereas OS were superimposable (97.3 ± 1.5% SE for CN-WT; 97.8 ± 1.5% SE for STN-WT96-99; 94.7 ± 1.0% SE for RR-WT67-95). Patients with STN-WT96-99 share the same excellent EFS and OS as patients with CN-WTs, and although this was achieved by more treatment for patients with STN-WT96-99 than for patients with CN-WT, reduction in postoperative treatment of these patients may be justified.