The most commonly mutated genes were TP53 and PIK3CA. We found that patients with TP53 mutations and a PIK3CA VAF of more than 1% in the ctDNA had significantly shorter PFS (Supplementary Figure S1B, S1C), thus indicating that TP53 and PIK3CA mutations may be poor prognostic factors for patients with breast cancer, as validated in several previous studies32–35. Here, PIK3CA is linked to breast cancer.