KRAS and Patent ductus arteriosus: Preamplification was performed using 5 μL cfDNA (equivalent to 100 μL plasma, containing 1.97 ± 0.61 ng DNA), and approximately 30% of the amplified template was utilized for the second‐run ddPCR assay, resulting in successful detection of the KRAS mutation in 8 (57.1%) of 14 KRAS mutant tumors (five CRC and nine PDA) samples (Table 2, Fig. 3, and Table S6).