PIK3CA and serous adenocarcinoma: For example, usually, low-grade serous carcinoma has ERBB2, BRAF and KRAS mutations (26), mucinous carcinoma has KRAS mutation (27), clear cell carcinoma has ARIDIA and PIK3CA mutations, and endometrioid cell carcinoma has CTNNB1, PTEN and PIK3CA mutations (28).