PIK3CA and neoplasm: In recent years, based on next-generation sequencing of circulating tumor DNA (ctDNA) detection, dynamic monitoring of molecular genetic changes occurring during TKI treatment of tumor patients through tumor rebiopsy can timely discover changes in bypass signals leading to resistance, such as MET gene amplification, HER2 gene amplification, KRAS gene mutation, PIK3CA gene mutation, etc. (69, 180, 201–203).