BG8 LewisY, also known as LewisY blood antigen or simply BG8, is a blood group antigen that has been identified in many studies as a potential marker for differentiation between pulmonary adenocarcinoma (PACA) and epithelioid mesothelioma (EM). It has been reported that sensitivity of non-mesothelial antigens for adenocarcinoma is organ-dependent. When attempting to differentiate epithelioid mesothelioma from adenocarcinoma, BG8 LewisY performed at a sensitivity of 98% in the breast cancer group, and 100% in the lung cancer group.