Extended Data Figure 1: Multiplex-PCR NGS platform analytical validation.

a, Analytical validation of the multiplex-PCR NGS platform was performed by spiking synthetic SNVs into control cfDNA. Sensitivity and specificity of the platform at different spike concentrations was ascertained, 95% binomial confidence interval displayed as error bars. b, Specificity of ctDNA detection based on a one-SNV and two-SNV call threshold taking into account parallel testing of multiple SNVs. c, The median read depth across a position did not vary depending on whether an SNV position was called or not called using the platform error model. Wilcoxon rank-sum test, P = 0.786. Median read depth at uncalled positions, 45,777; range, 0–146,774; n = 3,745. Median read depth at called positions, 45,478; range, 1,354–152,974; n = 1,124. Whiskers represent 1.5× the interquartile range, two-sided test.