TP53 and ovarian serous adenocarcinoma: On the other hand, high-grade serous ovarian cancer (HGSOC), high-grade endometrioid, undifferentiated cancers and carcinosarcomas often have high genomic instability, mutant TP53, defects in homologous recombination (HR) repair, mutations or impairment in BRCA1/2, and extensive copy number aberrations [6].