Articles

Tumor markers are an aid in monitoring the advancement of a neoplastic disease that has already been diagnosed.

They include various kinds of substances produced in excess by the diseased cells which can be measured in the patient's plasma or serum. Among the different markers available to the clinical practice, there is the chromogranin A (CgA).  

The CgA is an acidic glycoprotein of the weight of 48 Kd produced by neuroendocrine cells. It is a histotype non-selective kind of marker, but it's indicative of neuroendocrine proliferation.  

There are two methods to quantify the levels of this marker in the bloodstream: an immunoassay that allows detection in the plasma and a radioimmunoassay employing the serum.  

Elevated chromogranin A levels are present in a broad range of neuroendocrine tumors including carcinoids, pancreatic neoplasias, medullary thyroid tumors, pheochromocytomas, the pulmonary and extrapulmonary small cell cancer and breast, prostate, colorectal, rectum, thymus, larynx, liver and cervix cancers.  

The usefulness of the CgA assay goes beyond the follow-up of cases in which the presence of notably high values of this marker are detected, it also opens the possibility of an adjunctive therapy with, or relying on the exclusive use of, octreotide. This drug counters the proliferation of neuroendocrine cells and thus limits tumor progression.

However, it must be said that sometimes there are instances in which an elevated CgA value is not correlated to the presence of a neuroendocrine component in the pathology. Among such conditions, the most frequently met are renal failure, essential hypertension, atrophic gastritis, Parkinson's disease, prolonged use of proton pump inhibitors (such as omeprazole and derivatives) and pregnancy.

Dr. Carlo Pastore