Plasma cell-free DNA (cfDNA) as a predictive and prognostic marker in patients with metastatic breast cancer

Breast Cancer Research

Table 1 Descriptive statistics of variables and clinical characteristics of patients included in the study

Clinicopathological feature, observed at time of sample
Collection	Details	n	% of total
Age at time of sample collection (y*)	Median	59.50	–
	IQR*	20	–
	Range	29-89	–
Time spent in study^a (m*)	Median	23	–
	IQR*	27	–
	Range	1-59	–
Status^b	Alive	101	52.1
Status^b	Deceased	93	47.9
ER status	Positive	157	80.9
	Negative	30	15.5
	Unknown	7	3.6
PR status	Positive	115	59.3
	Negative	55	28.4
	Unknown	24	12.4
HER2 status	Positive	35	18.0
	Negative	133	68.6
	Unknown	26	13.4
CTCs/7.5 ml blood, by CellSearch®	Median	0.000	–
	IQR*	4.000	–
	Range	0-6848	–
	0–4	148	76.3
	≥ 5	46	23.7
cfDNA yield (ng/μl)	Median	0.120	–
	IQR*	0.175	–
	Range	0.003-5.460	–
	< 0.306	146	75.3
	≥ 0.306	48	24.7
CA15-3 (U/ml)	Median	49.000	–
	IQR*	149.250	–
	Range	1-6313	–
	< 32	67	34.5
	≥ 32	127	65.5
AP (IU/L)	Median	89.500	–
	IQR*	46.750	–
	Range	30-555	–
	< 130	154	79.4
	≥ 130	40	20.6
Treatment patient undergoing at the time of blood sampling	Endocrine	95	49.0
	Chemotherapy^c	49	25.3
	HER2-targeted therapy^d	18	9.3
	Off treatment	32	16.5
Disease response at time of blood sampling	Responding	30	15.5
	Stable disease	73	37.6
	Progressive disease	91	46.9

After screening and recruitment, patients were followed-up through the study. HER2 status was determined by immunohistochemical and fluorescence in situ hybridization assays. A patient was considered to have HER2-positive cancer if either assay was positive. CA15-3 and AP levels were determined form patient notes
IQR interquartile range, y years, m months
^aTime from collection to end of study or death
^bStatus of patients at the end of the study (deceased or alive)
^cChemotherapy +/− endocrine therapy
^dHER2 therapy +/− endocrine therapy

ISSN: 1465-542X