CEACAM5 and neoplasm: First LB methods were developed several decades ago and relied on the detection of tumor-derived proteins, such as carcinoembryonic antigen (CEA) [1, 2], prostate-specific antigen (PSA) [3, 4], ovarian cancer marker CA-125 [5, 6], etc. These techniques are currently routinely utilized during the diagnostic procedures, the assessment of the efficacy of surgical and therapeutic interventions, and the monitoring of the disease relapse [7, 8].