Table 2.

Concordance assessment of KRAS^G12/G13 mutations in formalin-fixed, paraffin-embedded (FFPE) tumor tissue and plasma cell-free DNA (cfDNA) from 121 patients with advanced cancers

	KRASG12/G13 mutation in tumor	KRASG12/G13 wild-type in tumor
Concordance for plasma samples (16 ng of cfDNA) collected before systemic experimental therapy tested with KRASG12/G13 multiplex probe versus FFPE tumor samples tested in the CLIA-certified laboratory
KRASG12/G13 mutation in cfDNA, no. of patients	74	4
KRASG12/G13 wild-type in cfDNA, no. of patients	14	29
Observed agreements	103 (85%); kappa, 0.66; SE, 0.07; 95% CI, 0.52–0.80
Sensitivity	84% (95% CI, 0.75–0.91)
Specificity	88% (95% CI, 0.72–0.97)
Positive predictive value	95% (95% CI, 0.87–0.99)
Negative predictive value	67% (95% CI, 0.51–0.81)
Concordance for plasma samples (16–100 ng of cfDNA) collected before systemic experimental therapy tested with KRASG12/G13 multiplex and/or mutation specific probes versus FFPE tumor samples tested in the CLIA-certified laboratory
KRASG12/G13 mutation in cfDNA, no. of patients	84	4
KRASG12/G13 wild-type in cfDNA, no. of patients	4	29
Observed agreements	113 (93%); kappa, 0.83; SE, 0.06; 95% CI, 0.72–0.95
Sensitivity	95% (95% CI, 0.89–0.99)
Specificity	88% (95% CI, 0.72–0.97)
Positive predictive value	95% (95% CI, 0.89–0.99)
Negative predictive value	88% (95% CI, 0.72–0.97)
Concordance for plasma samples (16–100 ng of cfDNA) collected before systemic experimental therapy tested with KRASG12/G13 multiplex and/or mutation specific probes versus FFPE tumor samples tested in the CLIA-certified laboratory or with droplet digital PCR
KRASG12/G13 mutation in cfDNA, no. of patients	86	2
KRASG12/G13 wild-type in cfDNA, no. of patients	4	29
Observed agreements	115 (95%); kappa, 0.87; SE, 0.5; 95% CI, 0.77–0.97
Sensitivity	96% (95% CI, 0.89–0.99)
Specificity	94% (95% CI, 0.79–0.99)
Positive predictive value	98% (95% CI, 0.92–1.00)
Negative predictive value	88% (95% CI, 0.72–0.97)

SE, standard error; CI, confidence interval.