Table 1.

Baseline patient characteristics (n = 27) and association with cfDNA levels and detection of ctDNA.

	n (%)a	Total cfDNA level by DFA		ctDNA detection by ddPCR
		ng/µl plasma	p-valueb	No	Yes	p-valuec
		Median (95% CI)		n (%)	n (%)
Age, median (range)	67 (40–90)
< 67 years	13 (48%)	0.73 (0.58–1.08)	0.55	6 (46%)	7 (54%)	0.71
≥ 67 years	14 (52%)	0.73 (0.60–0.89)		8 (57%)	6 (43%)
Sex
Female	10 (37%)	0.73 (0.58–0.97)	0.71	5 (50%)	5 (50%)	1.00
Male	17 (63%)	0.78 (0.60–1.06)		9 (53%)	8 (47%)
WHO performance status
0	8 (30%)	0.67 (0.50–0.94)	0.74d	6 (75%)	2 (25%)	0.62d
1–2	9 (33%)	0.75 (0.56–1.02)		5 (56%)	4 (44%)
Missing	10 (37%)	0.85 (0.58–1.50)		3 (30%)	7 (70%)
Primary tumor resected?
Yes	22 (81%)	0.68 (0.60–0.82)	< 0.01	13 (59%)	9 (41%)	0.17
No	5 (19%)	1.10 (0.78–1.91e)		1 (20%)	4 (80%)
Disease status
No evidence of disease	5 (19%)	0.62 (0.35–1.04e)	0.16f	4 (75%)	1 (25%)	0.06
Stable disease	10 (37%)	0.73 (0.60–0.89)	0.35f	7 (70%)	3 (30%)
Progressive disease	12 (44%)	0.81 (0.59–1.09)		3 (25%)	9 (75%)
Number of metastatic sites
0	5 (19%)	0.62 (0.35–1.04e)	0.35g	4 (80%)	1 (20%)	0.02
1	7 (26%)	0.86 (0.58–1.10)	0.53g	6 (86%)	1 (14%)
≥ 2	15 (56%)	0.75 (0.60–0.89)		4 (27%)	11 (73%)
Liver metastases?
No	19 (70%)	0.65 (0.59–0.91)	0.12	12 (63%)	7 (37%)	0.10
Yes	8 (30%)	0.81 (0.67–1.77)		2 (25%)	6 (75%)
Mutational status in tumor tissue
Wild-type	9 (33%)	0.73 (0.56–1.06)	0.78d	5 (56%)	4 (44%)	1.00d
Mutated	14 (52%)	0.69 (0.60–0.83)		7 (50%)	7 (50%)
Missing	4 (15%)	0.91 (0.72–1.10e)		2 (50%)	2 (50%)

WHO World Health Organization, cfDNA cell-free DNA.

^aPercentage may not total 100 due to rounding.

^bMann–Whitney U-test.

^cFisher’s exact test.

^dComparison not including patient with missing values.

^eUpper confidence limit held at maximum of sample.

^fCompared to 'progressive disease'.

^gCompared to 'Number of metastatic sites' ≥ 2.