PIK3CA and serous cystadenocarcinoma: Mutations in the gene encoding the catalytic subunit of PI3K p110α, PIK3CA, are found in nearly 33% of clear-cell carcinoma cases [5,6], 20% of endometrioid and clear-cell carcinomas [7], 18–28% of cases of serous cystadenocarcinoma, with enhancement of the signature of activated PI3K in the majority of ovarian cancer cases irrespective of the subtype [8].