The Therascreen PIK3CA RGQ PCR Kit (Qiagen Gmbh, Hilden, Germany), which is based on real-time qualitative PCR, is used for the detection of 11 mutations in the PIK3CA gene in FFPE tumor DNA or ctDNA of patients with breast cancer to identify patients for targeted treatment with PIQRAY® (Alpelisib). Here, PIK3CA is linked to breast carcinoma.