CCNE1 and ovarian cancer: (U.S. Cancer Statistics Working Group, 2019) Approximately 20% of high-grade serous carcinoma (HGSC), the most common subtype of ovarian cancer, have been found to harbor amplification of CCNE1, which codes for the cell cycle protein cyclin E. (Stronach et al., 2018) Patients with CCNE1-amplified HGSC have been shown to have a higher risk of chemoresistance to primary treatment and poor overall survival compared to those without CCNE1 amplification.