PIK3CA is a gene that encodes a lipid kinase involved in multiple signaling pathways. These pathways influence cellular functions such as growth, death, and proliferation. PIK3CA mutations activate the PI3K-PTEN-AKT pathway, which is downstream from both the EGFR and the RAS-RAF-MAPK pathways. PIK3CA mutations may cause oncogenic transformation independent of RAS or RAF mutations.
PIK3CA mutations occur in about 15% to 30% of breast, endometrial, and colon cancers.1, 2 They occur less frequently in lung cancer and other types of cancer. Presence of PIK3CA mutations is associated with poor prognosis and lack of response to specific therapies in patients with breast, endometrial, or colon cancer. In lung cancers, PIK3CA mutations can identify prognostically relevant subgroups.