a significant trendp < 0.001
Concentration of ctDNA was significantly different between stages of disease [ H (3) = 15.307, p = 0.002], with a significant trend of increasing ctDNA concentration associated with more advanced disease at diagnosis defined by NCCN clinical stage ( J = 1103.5, z = 3.737, p < 0.001, r = 0.46) (Fig. 2 ).