Chromogranin A as Blood Marker in Cancer Patients

Inclusion Criteria:

* Primary well-differentiated G1 and G2 neuroendocrine tumor located in jejunum, ileum, colon, rectum, duodenum, appendix, stomach, or pancreas
* Measurable disease according to RECIST criteria (Version 1.1)
* Eighteen years of age or older
* CT or MRI order obtained and within 4 weeks of CgA measurement
* BRAHMS CgA II KRYPTOR baseline measurement available
* Patient has discontinued the following treatments for at least 3 weeks before study start: i) proton pump Inhibitors (PPI), ii) corticoids, iii) H2-receptor antagonists
* Baseline Eastern Cooperative Oncology Group Performance Scale (ECOG PS) \<2
* Written informed consent signed

Exclusion Criteria:

* Other active malignancy with the exclusion of melanoma or other cancers that occurred more than 5 years ago
* Participation in another clinical trial involving an investigational therapeutic (exception: diagnostic studies and studies evaluating known therapies)
* No measurable disease by RECIST criteria (Version 1.1)
* Severe renal dysfunction defined as creatinine of 1.5x upper limit of normal (ULN)
* Severe liver dysfunction in the absence of liver metastasis defined by aspartate aminotransferase (AST), serum total bilirubin and/or alanine transaminase (ALT) 1.5x ULN; severe liver dysfunction in the presence of liver metastasis defined by AST and ALT over 5x ULN and total bilirubin over 1.5x ULN
* Severe gastrointestinal disorders (chronic atrophic gastritis, pancreatitis, inflammatory bowel disease, irritable bowel syndrome)
* Severe cardiovascular disease (severe symptomatic congestive heart failure, pulmonary artery hypertension, acute coronary syndrome)
* Patients receiving active treatment with the following medications and samples were collected less than 3 weeks after discontinuing: i) proton pump Inhibitors (PPI), ii) corticoids, iii) H2-receptor antagonists
* Chronic alcohol and/or substance abuse
* Known pregnancy