Table 1.

Characteristics of the patients and tumors.

Clinical Variable	Patients, No. (%)
Patients	35 (100%)
Sex
Male	18 (51%)
Female	17 (49%)
Age, years
1–10	29 (83%)
>10	6 (17%)
Diagnosis
Wilms tumor	14 (40%)
Neuroblastoma	10 (29%)
Ewing Sarcoma	4 (11%)
Rhabdomyosarcoma	4 (11%)
Others	3 (9%)
Tumor Volume
<50	5 (14%)
50–100	1 (3%)
101–500	16 (46%)
501–1000	8 (23%)
>1000	4 (11%)
Unknow	1 (3%)
Clinical Stage
I	1 (3%)
II	9 (26%)
III	10 (29%)
IV	13 (37%)
Unknow	2 (6%)
Metastasis at diagnosis
Yes	17 (49%)
No	18 (51%)
Metastasis during the treatment
Yes	11 (31%)
No	19 (54%)
Unknow	5 (14%)
cfDNA levels (ng/mL plasma)
<10	10 (29%)
10–50	13 (37%)
51–100	6 (17%)
>100	6 (17%)