Chromogranin A and serotonin for evaluation of treatment efficacy of neuroendocrine tumors

Background: The utility of biochemical markers in the monitoring of treatment efficacy in patients with neuroendocrine tumors (NETs) goes beyond any doubt. However, there are still no clear criteria for the assessment of clinically significant abnormalities of the main NET biomarkers chromogranin A (CgA) and serotonin. Aim: To evaluate the value of serial measurement of serum CgA and serotonin in the monitoring of the treatment effect in NET patients. Materials and methods: Serum CgA and serotonin levels were measured in 107 patients with NETs at baseline and at 3–4 weeks after the end of treatment (chemotherapy, biotherapy), as well as in 60 healthy controls. We used enzyme immunoassay based on Chromogranin A NEOLISA (Euro Diagnostica) and Serotonin ELISA (IBL International GmbH) test systems. Results: There was an association between CgA levels and the efficacy of chemotherapy in NET patients. With progression of the disease, median CgA increased significantly from 412 to 2679 ng/mL (p = 0.012), whereas in the patients with partial response it decreased from 811 to 254 ng/mL (p = 0.023). The ROC analysis showed the 33% cut-off for significant CgA changes for progression, with sensitivity of 80.0% and specificity of 95.6%. A decrease (of more than 33% compared to baseline levels) or absence of significant CgA changes was associated with stabilization of the disease or with partial response to treatment. Significantly decreased CgA levels were found in 75.0% cases of partial response and 43.48% of stabilized patients, whereas the absence of any significant changes in 25 and 66.7%, respectively. There was no association between serotonin levels and the disease behavior under treatment.Conclusion: CgA could be used as a sensitive marker of NET progression on chemotherapy.