ARID1A and ovarian clear cell cancer: ARID1A mutations/deletions are documented in up to 80% of clear cell ovarian cancer (CCC), 56% of uterine endometrioid cancer (EC) (43), 40% of endometrial carcinoma and endometroid ovarian cancer and 30% of mucinous ovarian cancer (44), but in 0% of high-grade serous ovarian cancer (44, 45).