The most comprehensive molecular study of endometrial cancer to date has been The Cancer Genome Atlas (TCGA) project, which revealed key molecular pathways and mutations associated with endometrial cancers; endometrioid subtypes most frequently had mutations of PTEN (a protein and lipid phosphatase), CTNNB1 (β-catenin), PIK3CA, and KRAS, along with microsatellite instability and POLE mutations (Table 2) whereas serous endometrial carcinomas are characterized by genetic alterations in the tumor suppressor TP53, HER2/neu, p16, and E-cadherin [105,106,107,108]. The gene discussed is PIK3CA; the disease is endometrial cancer.