Table 2.

Characteristics of the tumors.

Clinical Variable	Patients, No. (%)			Statistical Test
Clinical Stage	WT	NB	Sarcomas
I	0	0	1 (10%)	Not applied
II	6 (43%)	2 (20%)	1 (10%)
III	5 (36%)	0	5 (50%)
IV	3 (21%)	8 (80%)	2 (20%)
Unknow	0	0	1 (10%)
Correlation cfDNA levels vs. tumor staging
I/II vs. III	p = 0.99	-	p = 0.66	Mann-Whitney test and Kruskal-Wallis test.
I/II vs. IV	p = 0.99	p = 0.18	p = 0.05
III vs. IV	p = 0.99	-	p = 0.32
Correlation cfDNA levels vs. tumor volume
	p = 0.08	p = 0.02	p = 0.29	Spearmen test.
cfDNA levels and metastasis vs. no-metastasis at diagnosis
	p = 0.70	#	p = 0.12	Mann-Whitney test. # Statistics cannot be performed.
cfDNA levels and metastasis vs. no-metastasis during treatment
	p = 0.94	#	p = 0.50	Mann-Whitney test. # Statistics cannot be performed.