Apart from alterations in a few well-known drivers, including KRAS and HER2 amplification, in ovarian serous and mucinous carcinomas and mutations in ARID1A, PIK3CA, and PTEN genes as well as mismatch repair (MMR) deficiency in ovarian endometrioid carcinomas, comparatively little is known about molecular alterations in these tumors (12). This evidence concerns the gene PIK3CA and ovarian endometrioid carcinoma.