CD274 and ovarian carcinoma: Due to high heterogeneity of ovarian cancer and different expression profile of PD-L1, these data should be interpreted with caution as PD-L1 expression in some OC subtypes (but not in all OC subtypes) i.e. high grade serous OC [55, 57, 58] and clear cell carcinoma [18] can have prognostic relevance.