Table 1.

Clinical characteristics of the patients included in the study at the time of sample collection. General characteristics of the main groups of patients included in the study are shown. CNS: Central nervous system

	Metastatic patients with CNS disease (n = 42)		Metastatic patients without CNS disease (n = 50)		Healthy/cured controls (n = 31)
Histological type of the primary tumor	n	%	n	%	n	%
Lung cancer	13	31	12	24	_	_
Breast cancer	14	33	21	42	_	_
Kidney cancer	4	10	10	20	_	_
Melanoma	11	26	7	14	_	_
Number of previous systemic therapies received for metastatic disease
0	18	43	28	56	_	_
1 or more	24	57	22	44	_	_
Type of systemic therapies received for metastatic disease
Chemotherapy	17	40	11	22	_	_
Immune checkpoint inhibitors	7	17	4	8	_	_
Targeted therapy (including hormone therapy)	24	57	33	66	_	_
No systemic treatment	18	43	28	56	_	_
Previous oncological history
No oncological history	_	_	_	_	10	32
Breast cancer	_	_	_	_	9	29
Testicular tumor (germ cell)	_	_	_	_	12	39
Time elapsed since curative treatment
5–7 years	_	_	_	_	13	42
7–10 years	_	_	_	_	5	16
>10 years	_	_	_	_	3	10
Previous adjuvant/neoadjuvant systemic treatment
Chemotherapy	_	_	_	_	15	49
No systemic treatment	_	_	_	_	6	19