4. Pathological Diagnosis and Tumor Markers

Pulmonary and digestive neuroendocrine tumors (NETs) are a group of neoplasms whose incidence and prevalence has been constantly increasing over the last years thanks to the significant improvements in instrumental diagnostic techniques. Because NETs are extremely heterogeneous a correct histopathological diagnosis is essential for appropriate treatment. More specifically, the histopathological diagnosis of NETs can be regarded as a multistep: identification of the neuroendocrine nature of the neoplasm, determination of tumor grading; identification of unknown primary. Laboratory biomarkers for the study of gastroenteropancreatic neuroendocrine tumors include both specific markers and non-specific or general markers. At the moment, chromogranin A is the best available and most frequently used biomarker for the diagnosis of NETs, offering the highest overall sensitivity. CgA has also demonstrated some utility in the assessment of response to treatment and as indicator of tumor recurrence.