Molecular Pathology of Ovarian Tumors

Ovarian cancer is associated with high morbidity and mortality and is the leading cause of gynecologic cancer-related death in the US. In recent years, the molecular pathophysiology of ovarian tumors has been better elucidated, allowing for the distinction of two tumor types: the more indolent type I tumors (encompassing endometrioid, clear cell, low-grade serous, and mucinous carcinomas) and the highly aggressive type II tumors (encompassing high-grade serous carcinomas and carcinosarcomas). Type I tumors are related to abnormalities in the MAPK signaling pathway (KRAS and BRAF mutations), the PI3K/Akt2/PTEN pathway, and the Wnt/beta-catenin pathway, as well as mutations in other genes such as ARID1a, PPP2R1A, and HNF1-beta. Type II tumors, in contrast, are characterized by mutations in TP53, as well as inactivation of BRCA1/2 and mutations in genes such as Notch3, Rsf-1, and NAC1. In this chapter, we discuss the characteristics and frequency of these molecular abnormalities, with an emphasis on their implications for diagnosis and treatment.