PIK3CA and neoplasm: Compared with KRAS HS values (median 1.05, IQR 0.59–1.66), significantly higher EGFR HS values (median 1.23, IQR 0.68–1.99, P = 0.037) were observed, indicating that mutant allele‐specific imbalance (MASI) may be a common event in EGFR. Moreover, BRAF (median 0.62, IQR 0.27–0.83, P = 0.022) and PIK3CA HS values (median 0.55, IQR 0.23–1.33, P = 0.039) were lower than KRAS HS values, indicating that BRAF and PIK3CA mutations are more likely to be present in a subclonal tumor population.