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Table 2 Overall concordance between ctDNA and tissue DNA based on time interval between blood draw and tissue biopsy and on whether primary or metastatic tumor was biopsied (N = 66)

From: Clinical correlates of blood-derived circulating tumor DNA in pancreatic cancer

Patients with pancreatic ductal adenocarcinoma who had both ctDNA and tissue DNA sequencing (N = 66)  
  Tissue DNA (+)Tissue DNA (−)Overall concordance* (%)Kappa (SE)  
TP53ctDNA (+)29 (44%)4 (6.1%)610.21 (0.1)  
ctDNA (−)22 (33%)11 (17%)  
KRASctDNA (+)28 (42%)0 (0.0%)520.14 (0.1)  
ctDNA (−)32 (48%)6 (9.1%)  
Concordance depending on whether primary tumor or metastatic site was biopsied
  Primary tumor (n = 41)Metastatic sites (n = 25) 
  Tissue DNA (+)Tissue DNA (−)Overall concordance* (%)Kappa (SE)Tissue DNA (+)Tissue DNA (−)Overall concordance* (%)Kappa (SE)P value
TP53ctDNA (+)14 (34%)1 (2.4%)540.19 (0.1)15 (60%)3 (12%)720.27 (0.2)0.20
ctDNA (−)18 (44%)8 (20%)4 (16%)3 (12%)
KRASctDNA (+)14 (34%)0 (0.0%)390.05 (0.04)14 (56%)0 (0.0%)720.39 (0.2)0.01
ctDNA (−)25 (61%)2 (4.9%)7 (28%)4 (16%)
Concordance based on time interval between blood draw and tissue biopsy
  ≤ 6 months (n = 49)>6 months (n = 17) 
  Tissue DNA (+)Tissue DNA (−)Overall concordance* (%)Kappa (SE)Tissue DNA (+)Tissue DNA (−)Overall concordance* (%)Kappa (SE)P value
TP53ctDNA (+)25 (51%)3 (6.1%)650.24 (0.1)4 (24%)1 (5.9%)470.10 (0.2)0.25
ctDNA (−)14 (29%)7 (14%)8 (47%)4 (24%)
KRASctDNA (+)22 (45%)0 (0.0%)550.17 (0.1)6 (35%)0 (0.0%)410.07 (0.1)0.40
ctDNA (−)22 (45%)5 (10%)10 (59%)1 (6%)
  1. *Genomic concordance was analyzed in this table rather than molecular locus concordance