Figure 2. Plasma circulating tumor DNA (ctDNA) mutant concentration increased with higher stage (p for trend <0.001). Bars show the highest and lowest values, except outliers (◯), which are 1.5 to 3 box lengths from the end of the box, and extremes (*) which are more than 3 box lengths from the end of the box. Concentrations of ctDNA in stage III and IV were significantly higher compared with stage I (p=0.025 and 0.007, respectively). One-way ANOVA with Bonferroni correction and trends across ordered groups were analyzed using linear regression with log-transformed values.