CD274 and ovarian carcinoma: Expression of PD-L1 is prevalent among many tumors, including lung cancer, ovarian cancer, melanoma, brain tumors, malignant lymphoma, multiple myeloma, and colon cancer, and its overexpression is associated with poor prognosis in a number of cancers, including renal cancer, melanoma, lung cancer, ovarian cancer, and colon cancer [3–8].