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Table 1 Baseline patient and tumor characteristics stratified by CTC count and CTC clusters

From: Longitudinal enumeration and cluster evaluation of circulating tumor cells improve prognostication for patients with newly diagnosed metastatic breast cancer in a prospective observational trial

  All patients Baseline CTC < 5 Baseline CTC ≥5 P value Baseline clusters absent Baseline clusters  ≥ 1 P value
(n = 156) (n = 73) (n = 79) (n = 122) (n = 30)
Age MBC, median (range) 65 (40–90) 65 (40–-84) 65 (41–90) 0.71a 67 (40–90) 60 (42–72) 0.002a
Baseline ECOG
 0 91 48 (53) 43 (47) 0.07b 76 (84) 15 (16) 0.32b
 1 37 17 (46) 20 (54) 29 (78) 8 (22)
 2 22 6 (30) 14 (70) 15 (75) 5 (25)
 Unknown 6       
PT NHG
 I 13 9 (69) 4 (31) 0.58b 12 (92) 1 (8) 0.85b
 II 65 26 (41) 38 (59) 47 (73) 17 (27)
 III 46 22 (49) 23 (51) 38 (84) 7 (16)
 Unknown 32      
PT tumor size
 T1 57 30 (55) 25 (45) 0.16b 49 (89) 6 (11) 0.07b
 T2 51 25 (49) 26 (51) 39 (76) 12 (24)
 T3 20 8 (40) 12 (60) 15 (75) 5 (25)
 T4 19 7 (39) 11 (61) 13 (72) 5 (28)
 Unknown 9      
PT node status
 Negative 44 27 (61) 17 (39) 0.04c 39 (89) 5 (11) 0.10c
 Positive 92 38 (42) 52 (58) 69 (77) 21 (23)
 Unknown 20       
Breast cancer subtyped
 ER+ HER2- 105 46 (44) 58 (56) 0.52c 86 (83) 18 (17) 0.34c
 HER2+ 20 11 (58) 8 (42) 14 (74) 5 (26)
 ER- HER2- 26 12 (50) 12 (50) 17 (71) 7 (29)
 Unknown 5       
Metastasis-free interval (years)
 0 31 14 (47) 16 (53) 0.57b 24 (80) 6 (20) 0.97b
  > 0-3 28 11 (41) 16 (59) 22 (81) 5 (19)
  > 3 97 48 (51) 47 (49) 76 (80) 19 (20)
Metastatic sites, number
  < 3 109 58 (54) 49 (46) 0.02c 88 (82) 19 (18) 0.34c
  ≥ 3 47 15 (33) 30 (67) 34 (76) 11 (24)
Site of metastasis
 Non-visceral 65 29 (45) 35 (55) 0.57c 47 (73) 17 (27) 0.07c
 Viscerale 91 44 (50) 44 (50) 75 (85) 13 (15)
1st line treatment for MBCf
 Endocrine 58 31 (53) 27 (47) 0.28c 56 (97) 2 (3) < 0.001c
 Chemotherapy 71 29 (42) 40 (58) 48 (70) 21 (30)
 HER2-targeted 15 9 (60) 6 (40) 11 (73) 4 (27)
One or more clusters of ≥ 2 CTCs at baselineg
 No 122 73 (60) 49 (40) < 0.001c    
 Yes 30 0 30 (100)    
  1. Abbreviations: CTC circulating tumor cell, MBC metastatic breast cancer, ECOG Eastern Cooperative Oncology Group, NHG Nottingham histological grade, PT primary tumor, ER estrogen receptor, HER2 human epidermal growth factor receptor 2
  2. aP value from Mann-Whitney test
  3. bP value from Pearson’s chi-squared test for trend
  4. cP value from Pearson’s chi-squared test
  5. dBreast cancer subtype was primarily derived from immunohistochemical staining of the metastasis (n = 114). If no information was available from the metastasis, the subtype was derived by staining of the primary tumor (n = 36)
  6. eVisceral metastasis defined as lung, liver, brain, peritoneal, and/or pleural involvement
  7. fA total of 12 patients died and/or treatment was ended before the first structured clinical follow up at 3 months post treatment initiation and consequently no data are available for these patients
  8. gFour patients had no baseline sample and thus had no data on CTCs and CTC clusters