In addition, five new proteins with increased expression in ovarian cancer sera were identified: alpha-1-antitrypsin (AAT), apolipoprotein E (APOE), extracellular matrix protein-1 (ECM1), inter-alpha globulin inhibitor-H3, orosomucoid-2 (ORM2; Figure 1; Additional file 1, Table S1). Here, APOE is linked to ovarian cancer.