MKI67 and neoplasm: Among these factors, tumors diagnosed with diffused midline glioma (DMG), H3K27-altered tumor (12/14 vs 3/22, P = 0.0002), reaching the surface of the spinal cord in MRI imaging (13/21 vs 1/11, P = 0.012), and Ki-67 index >=10% (13/22 vs 2/14, P = 0.014) showed higher rate of ctDNA positivity compared to others (Fig. 2a–c).