PIK3CA and breast cancer: Figure 1 summarized the mutation landscape of Chinese early-stage breast cancer. TP53 (47.0%), PIK3CA (45.0%), and ERBB2 (30.0%) were the most frequently mutated genes in our cohort. Other genes that were mutated in ≥10% of the patients included CDK12 (18.0%), GATA3 (15.0%), CCND1 (12.0%), FGF19 (11.0%), and FGFR1 (10.0%).