Clinical characteristics and outcome of Wilms tumors with a favorable histology in Japan: a report from the Study Group for Pediatric Solid Malignant Tumors in the Kyushu Area, Japan

Characteristics and Outcome of Children with Renal Cell Carcinoma: A Narrative Review

Pediatric renal cell carcinoma (RCC) is a rare type of kidney cancer, most commonly occurring in teenagers and young adolescents. Few relatively large series of pediatric RCC have been reported. Knowledge of clinical characteristics, outcome and treatment strategies are often based on the more frequently occurring adult types of RCC. However, published pediatric data suggest that clinical, molecular and histological characteristics of pediatric RCC differ from adult RCC. This paper summarizes reported series consisting of ≥10 RCC pediatric patients in order to create an up-to-date overview of the clinical and histopathological characteristics, treatment and outcome of pediatric RCC patients.

Minimally invasive surgery in management of renal tumours in children

Minimally invasive surgery (MIS) in the management of malignant and benign renal tumours in children is gradually becoming more common. Experience is limited and restricted to case reports, retrospective chart reviews and a few cohort studies. There are currently no randomized controlled trials or controlled clinical trials comparing the laparoscopic and open surgical approach for the management of renal tumours in children. MIS may offer the same oncologic outcome in malignant renal tumours whilst providing the advantages associated with MIS in correctly selected cases. The technique for tumour resection has been shown to be feasible in regards to the recommended oncologic principles, although lymph node sampling can be inadequate in some cases. Preliminary reports do not show an increased risk of tumour rupture or inferior oncologic outcomes after MIS. However, the sample size remains small and duration of follow-up inadequate to draw any firm conclusions. Implementation of MIS is lacking in the protocols of the major study groups, and standardized recommendations for the indications and contra-indications remain undefined. The objective of this article is to present a review of the literature on the role of MIS in the management of renal tumours in children, with the main focus on Wilms' tumour (WT). Further studies on MIS in renal tumours are required to evaluate the incidence of oncological complications such as complete tumour resection and intra-operative tumour spillage. A long-term follow-up of patients managed by MIS is essential to compare recurrence rates and overall survival rates.

The prognostic significance of blastemal predominant histology in initially resected Wilms' tumors: a report from the Study Group for Pediatric Solid Tumors in the Kyushu Area, Japan

BACKGROUND AND PURPOSE

The strategy used to treat pediatric renal tumors in Japan is based on the Japanese Wilms' Tumor Study (JWiTS) protocol, which was based on the National Wilms' Tumor Study (NWTS)-5 regimen. The regimen is characterized by an initial radical operation, followed by adjuvant chemotherapy and radiotherapy. Concerning the histological classification, a new classification based on the International Society of Pediatric Oncology (SIOP) classification was used beginning in 2008. The main points of revision are that the "blastemal predominant type" was classified as an independent category in the Wilms' tumor subtypes. The purpose of this study was to analyze the biological characteristics from the standpoint of the newly established histological classification.

MATERIALS AND METHODS

From 1971 to 2005, 174 cases of Wilms' tumors treated with an initial operation followed by adjuvant therapy were re-evaluated by the new histological classification. Histologically, all these materials showed no secondary changes associated with adjuvant therapy.

RESULTS

According to the new classification, Wilms' tumors were classified into four subtypes, including the mixed type (n=112), epithelial type (n=17), mesenchymal type (n=15), and blastemal predominant type (n=26). The 5 year overall survival rates were as follows; mixed type (90.1%), epithelial type (100%), mesenchymal type (93.3%), and blastemal predominant type (65.4%).

CONCLUSION

The patients with blastemal predominant tumors demonstrated a significantly worse prognosis compared with those of other subtypes. The treatment strategy of blastemal predominant category should be distinguished from the other favorable subtypes.

Wide range and variation in minimally invasive surgery for renal malignancy in Japan: a population-based analysis

BACKGROUND

Despite increasing interest in minimally invasive surgery, prevalence data are completely absent. Our objective was to analyze clinico-epidemiological variations of surgery for renal malignancy in Japan with emphasis on annual trends and regional gaps, and to analyze factors affecting choice of open versus minimally invasive surgery.

METHODS

We identified patients who underwent open (n = 8646), laparoscopic (n = 5932), or minimum incision endoscopic surgery (MIES) (n = 381) nephrectomy for renal malignancy, using the Japanese Diagnosis Procedure Combination database, 2007-2010. Clinical and regional variations in these three approaches were determined, and the annual per-population incidence of nephrectomy was estimated. Multivariate logistic regression was used to analyze factors affecting choice of minimally invasive surgery (laparoscopy or MIES).

RESULTS

The proportion of open nephrectomy decreased from 65.3 % in 2007 to 51.6 % in 2010. Laparoscopic nephrectomy accounted for 51.0 % of procedures for T1 tumors. The estimated incidence of nephrectomy in males and females was 14.3 and 6.1 per 100,000 person-years, respectively. Multivariate analysis showed that minimally invasive nephrectomy was more likely to be selected for patients in their 30-50s who had less comorbidity, better performance status, or lower TNM stage, in high-volume or academic hospitals, especially in western Japan. Hemodialysis use was a favorable factor.

CONCLUSION

Despite differences between eastern and western Japan, minimally invasive surgery is becoming widespread throughout Japan, especially for patients with low operative risks and early-stage cancer who are hospitalized in high-volume institutes.

Prechemotherapy laparoscopic nephrectomy for Wilms' tumor

Laparoscopic radical nephrectomy is emerging as the treatment of choice for localized renal malignancies in adults. Despite the widespread use of laparoscopic nephrectomy for benign renal disease in infants and children, the laparoscopic approach has not been employed for pediatric Wilms' tumor except following systemic chemotherapy. We report the results of laparoscopic radical nephrectomy for removal of unilateral Wilms' tumor prior to the administration of systemic chemotherapy in two patients.