Clinical, pathological and loss of heterozygosity differences in Wilms tumors between Asian and non-Asian children

Epidemiologic and Clinical Outcomes of Pediatric Renal Tumors in Korea: A Retrospective Analysis of The Korean Pediatric Hematology and Oncology Group (KPHOG) Data

PURPOSE

Renal tumors account for approximately 7% of all childhood cancers. These include Wilms tumor (WT), clear cell sarcoma of the kidney (CCSK), malignant rhabdoid tumor of the kidney (MRTK), renal cell carcinoma (RCC), congenital mesoblastic nephroma (CMN) and other rare tumors. We investigated the epidemiology of pediatric renal tumors in Korea.

MATERIALS AND METHODS

From January 2001 to December 2015, data of pediatric patients (0-18 years) newly-diagnosed with renal tumors at 26 hospitals were retrospectively analyzed.

RESULTS

Among 439 patients (male, 240), the most common tumor was WT (n=342, 77.9%), followed by RCC (n=36, 8.2%), CCSK (n=24, 5.5%), MRTK (n=16, 3.6%), CMN (n=12, 2.7%), and others (n=9, 2.1%). Median age at diagnosis was 27.1 months (range 0-225.5) and median follow-up duration was 88.5 months (range 0-211.6). Overall, 32 patients died, of whom 17, 11, 1, and 3 died of relapse, progressive disease, second malignant neoplasm, and treatment-related mortality. Five-year overall survival and event free survival were 97.2% and 84.8% in WT, 90.6% and 82.1% in RCC, 81.1% and 63.6% in CCSK, 60.3% and 56.2% in MRTK, and 100% and 91.7% in CMN, respectively (p < 0.001).

CONCLUSION

The pediatric renal tumor types in Korea are similar to those previously reported in other countries. WT accounted for a large proportion and survival was excellent. Non-Wilms renal tumors included a variety of tumors and showed inferior outcome, especially MRTK. Further efforts are necessary to optimize the treatment and analyze the genetic characteristics of pediatric renal tumors in Korea.

Comparative analysis of the clinical characteristics and outcomes of patients with Wilms tumor in the United Kingdom and Japan

BACKGROUND

Wilms tumor (WT) demonstrates epidemiological differences by world region and ethnicity. To enhance understanding of these differences, we retrospectively analyzed clinical trial data sets from the UK and Japan over a 20-year period.

PROCEDURE

We used data from three consecutive clinical trials in the UK and a single study in Japan that enrolled patients diagnosed during 1996-2015, to compare clinical characteristics and outcomes between countries.

RESULTS

During 1996-2015, 1395 patients in the UK and 537 in Japan were included. Japanese patients have a significantly younger median age at diagnosis than those in the UK (28 months vs 39 months). The proportion of patients with stage IV, large tumors, and anaplastic histology appears to be higher in the UK than in Japan (18% vs 11%, 62% vs 49%, 8% vs 3%, respectively). During 2005-2015, 77 hospitals treated WT in Japan compared with only 20 hospitals in the UK. Five-year overall survival of patients with WT was over 90% in both countries, but five-year event-free survival of patients with stage IV was significantly lower in Japan than in the UK (50.0% vs 76.2%, P = 0.001).

CONCLUSIONS

Differences in age of onset, tumor size at diagnosis, and histology may reflect differences in the genetic background of patients with WT between countries, but population-based phenotype-genotype data are lacking. The difference in survival probability for stage IV patients may be due to different diagnostic criteria or different treatment strategies. Prospective, international clinical studies including genomic analyses are needed to confirm these findings and improve clinical practice.

Diagnostic accuracy and cytomorphological spectrum of Wilms tumour in fine needle aspiration biopsy cytology samples supplemented with cell blocks

OBJECTIVE

Paediatric malignant renal neoplasms are subjected to neoadjuvant chemotherapy as per Societe Internationale d'Oncologie Pediatrique; International Society of Pediatric Oncology (SIOP) protocol. An accurate tissue diagnosis is required prior to institution of chemotherapy, and hence the aim of this study was to evaluate the diagnostic accuracy of fine needle aspiration biopsy cytology (FNABC) along with cell block histology.

MATERIALS AND METHODS

A retrospective audit of all paediatric renal neoplasms diagnosed by FNABC between 2015 and 2019 was performed. Histopathology correlation was done wherever available. WT cases were subjected to detailed cytomorphological evaluation.

RESULTS

A total of 121 cases of paediatric renal neoplasms including 109 WT, four clear cell sarcoma, one malignant rhabdoid tumour and three mesoblastic nephroma were evaluated. The age range was 4 weeks to 8 years. FNABC samples were adequate for diagnosis in 120 of 121 cases (99.18%) and a definitive cytological diagnosis was achieved in 117 cases (96.7%). The specificity and sensitivity for a cytopathological diagnosis of WT were 98.7% and 97.4%, respectively. On detailed cytomorphological analysis of 68 histopathology-proven WT, 40 (58.8%) cases were triphasic, 23 (35.3%) were biphasic and four were composed of blastema only. The corresponding cell blocks provided additional information over the conventional smears in 23 (33.8%) cases, with epithelial or mesenchymal elements recognised and evidence of rhabdomyoblastic differentiation.

CONCLUSION

FNABC along with cell block histology is highly accurate for diagnosis of WT and other malignant paediatric renal neoplasms and is recommended as the technique of choice in centres with cytopathology expertise for establishing a cellular diagnosis prior to commencement of neoadjuvant chemotherapy.

Loss of Heterozygosity at Chromosome 16q Is a Negative Prognostic Factor in Korean Pediatric Patients with Favorable Histology Wilms Tumor: A Report of the Korean Pediatric Hematology Oncology Group (K-PHOG)

PURPOSE

Loss of heterozygosity (LOH) at chromosomes 1p and 16q is a poor prognostic factor in favorable histology Wilms tumor (FHWT). This study investigated the prevalence of LOH at 1p and 16q and evaluated its prognostic value in Korean children with FHWT.

MATERIALS AND METHODS

We analyzed 101 FHWT patients who were diagnosed between 1996 and 2016 in Korean Society of Pediatric Hematology Oncology Group hospitals. Using paraffin-embedded kidney tissue samples sent from each center, we reviewed LOH at 1p and 16q in each patient and assessed the prognostic value of LOH status for clinical parameters affecting event-free survival (EFS).

RESULTS

Of the 101 patients, 12 (11.9%) experienced recurrence; the 3-year EFS was 87.6%. LOH at 1p or 16q was detected in 19 patients (18.8%), with five having LOH at both 1q and 16q. The frequency of LOH at 1p was higher among younger patients (p=0.049), but there was no difference in LOH prevalence according to tumor stage. In the multivariate analysis, LOH at 16q was a significant negative prognostic factor affecting EFS (3-year EFS, 73.7% vs. 91.1%; hazard ratio, 3.95; p=0.037), whereas LOH at 1p was not (p=0.786).

CONCLUSION

LOH at 16q was a significant negative prognostic factor affecting outcome in Korean pediatric FHWT patients. Due to the small sample size of this study, large-scale multicenter trials are warranted to investigate the prognostic value of LOH at 1p and 16q in Korean children with FHWT.