We also analyzed whether the amount of PIK3CA-mutant cfDNA correlated with discrepancies between cfDNA and tumor tissue and patients with concordant results in cfDNA and tumor tissue had a median of 1.83% of PIK3CA-mutant cfDNA compared to a median of 2.61% of PIK3CA-mutant cfDNA in patients with discrepant results (p = 0.50). The gene discussed is PIK3CA; the disease is neoplasm.