Importance of biochemical markers in routine oncological practice (according to materials of clinical recommendations)

Background. The diagnostics of neuroendocrine tumors (NET) is complex due to many factors such as the heterogeneity of the tumors themselves, different localization of the tumor process, and the presence of severe hormonal syndromes. A special place in the diagnostic search is given to the study of biochemical markers which are conditionally divided into universal and specific ones. Materials and methods. Chromogranin A (CGA) is a universal marker that in most cases identifies tumors of a neuroendocrine nature and is characterized by the best combination of diagnostic sensitivity and specificity. Pancreatic polypeptide (PP) and neuron-specific enolase (NSE) are determined in addition to CGA in pancreatic tumors and in low-grade forms of neuroendocrine cancer. Specific markers, serum serotonin and its metabolite in daily urine 5-hydroxyindolacetic acid (5-GIUC), are the generally recognized specific markers for diagnosing of carcinoid syndrome. Other specific markers such as gastrin, insulin, glucagon, and others, are associated with certain hyperfunctional syndromes and are being investigated to confirm their presence. The article presents generalized recommendations for the use of biochemical markers, taking into account the existing clinical signs, syndromes, and types of NETs. To monitor the course of the tumor process and evaluate the effectiveness of treatment in patients with an established diagnosis of NET, it is recommended to determine the biochemical markers with increased basal levels. At the same time, there is a need to standardize the survey timing. For more accurate monitoring and interpretation of data, serial marker studies should be performed with the same test systems used in the same specialized laboratory.