SPP1 and cancer: Recently, the use of serum proteins (CA-125, CA-199, CEA, prolactin, hepatocyte growth factor, osteopontin, myeloperoxidase, and tissue inhibitor of metalloproteinases-1) in combination with 13 cell-free (cf)-DNA amplicons (NRAS, CTNNB1, PIK3CA, FBXW7, APC, EGFR, BRAF, CDKN2A, PTEN, FGFR2, HRAS, AKT1, TP53), i.e., the “CancerSEEK” blood test, was reported to detect multiple cancers, including OC [24, 25].