Table 1

Characteristics of registered patients with Wilms’ tumour treated with preoperative chemotherapy according to the SIOP WT 2001 trial protocol in Germany and the UK and Republic of Ireland

Characteristic	GPOH		CCLG		p Value	Statistical test
Total number patients*	951		616
Median age at diagnosis (months)	40.4		40.4		0.902	Rank-sum test
Tumour stage distribution		%		%	<0.001	χ² (3 df)=73.64
Stage I	524	55.1	219	35.6
Stage II	172	18.1	136	22.1
Stage III	107	11.3	150	24.4
Stage IV	148	15.6	111	18
Stage I–III (all localised tumours)	803	84.4	505	82	0.227	χ² (1 df)=1.46
Stage IV (metastatic tumours)	148	15.6	111	18
Histological risk group
Low risk	49	5.2	39	6.3	0.568	χ² (2 df)=1.13
Intermediate risk	780	82.0	503	81.7
High risk	122	12.8	74	12.0
Tumour size (mL)
Tumour volume at diagnosis	381.8		572		<0.001	Rank-sum test
IQR	197.8, 627.6		334.7, 903.7

*The UK registered 18% of all patients until December 2011, when it closed the study to national recruitment, after the closure of the randomised trial arm, for which only a subgroup of all WT patients were eligible. All other European countries continue to register patients.
CCLG, Children's Cancer and Leukaemia Group; GPOH, Gesellschaft für Pädiatrische Onkologie und Hämatologie).