Based on a 95% confidence interval, the PI3KCA E545K mutation was detected in both spiking samples analyzed, with 52.9 [95% CI: 35.7–70.2] copies detected in one sample of 114 spiked MCF‐7 cells among 72,657 PIK3CA WT [95% CI: 71,990–73,336] copies (Figure S3E) and 94.3 [95% CI: 71.3–117.3] copies detected in a sample with 182 MCF‐7 cells among 156,055 PIK3CA WT [95% CI: 155,020–157,090] copies (Figure S3F), indicating nearly linearity in this assay and good correspondence with the amount of tumor cells per sample. Here, PIK3CA is linked to neoplasm.