Is the SIOP-2001 Classification of Renal Tumors of Childhood accurate with regard to prognosis? A problem revisited.
BACKGROUND
The goal of this study was to analyze morbidity and mortality of Wilms' tumor based on the revised SIOP-2001 classification.


METHODS
Sixty-four patients with unilateral Wilms' tumor, 33 girls (51.5%) and 31 boys (48.5%), aged 1 to 144 months (mean: 42.8 months) were treated between 1993 and 2009. All patients underwent multimodal therapy according to the SIOP protocols. The follow-up period ranged from 2 to 18 years (mean: 11.6 years).


RESULTS
Thirty-three patients (51.6%) had intermediate-risk, 6 (9.4%) low-risk and 25 (39%) high-risk tumors. Stage I disease was diagnosed in 28 (43.7%), stage II in 19 (29.7%), stage III in 8 (12.5%) and stage IV in 9 patients (14.1%). Event-free survival (EFS) in the entire group was 78.1% and OS was 92.2%. The EFS in stage IV (44.4%) was significantly lower than in stage I (82.1%, p = 0.04), stage II (89.5%, p = 0.02) and in the entire group (78.1%, p = 0.04). Sixteen complications were observed in 14 children (21.9%); metastases in 7 cases (10.9%), 8 relapses (12.5%) and 5 deaths (7.8%). Blastemal (20/24 - 83.3%) and anaplastic (3/24 - 12.5%) subtypes were responsible for mortality in high-risk tumors (OS - 87.5%), while poorly differentiated epithelial (7/34 - 20.6%) and regressive (8/34 - 23.5%) subtypes decreased OS (94.1%) in the intermediate-risk tumors.


CONCLUSIONS
The results of our study show that epithelial and regressive subtypes were responsible for mortality in the intermediate-risk Wilms' tumors.
Department of Pediatric Surgery and Urology, University Children's Hospital No. 4, Medical University of Lodz, Poland.
Jerzy
J
Niedzielski
Katarzyna
K
Taran
Wojciech
W
Młynarski
Anna
A
Sitkiewicz