Is the combination of chromogranin A and pancreatic polypeptide serum determinations of interest in the diagnosis and follow-up of gastro-entero-pancreatic neuroendocrine tumours?
This chapter covers endocrine cancers, including typical thyroid cancer as well as medullary thyroid carcinoma (MTC). Adrenal tumours, associated with Cushing's syndrome, and Conn's syndrome, associated with pituitary tumours, are discussed in detail. It includes information on epidemiology, clinical features, pathology, diagnosis, treatment, follow-up, and prognosis. It also covers special problems in pregnancy. Special attention is made to merging techniques in molecular oncology, which have led to biomarker-driven therapy of thyroid and pancreatic neuroendocrine tumours with biologic agents. For pancreatic neuroendocrine tumours, special attention is made to new imaging techniques and therapy for patients with syndrome associated with peptide hormone release.
The measurement of general and specific biochemical markers in patients with neuroendocrine tumours assists with diagnosis and gives an indication of the effectiveness of treatment and they may be used as prognostic indicators. There is much agreement that chromogranin A is the most universally helpful marker; it is found to be elevated in the circulation of about 90% of patients with metastatic neuroendocrine tumours and there are several excellent commercially available kits which give reliable estimations. Specific markers are useful for diagnosis also, and are helpful indicators of the effectiveness of treatment, particularly where tumour bulk may not change as much as tumour activity. Sporadic pancreatic neuroendocrine tumours may secrete more than one peptide and this indicates a worsening prognosis. Because of the wide variation in the progression of neuroendocrine tumours, a prognostic indicator gives a significant advantage to the clinician in order to facilitate optimum treatment at the optimum stage of disease. Both chromogranin A and neurokinin A have been used as powerful prognostic indicators for midgut carcinoid tumours.
Small non-functioning pancreatic NETs (pNETs) ≤2 cm can pose a management dilemma in terms of surveillance or resection. There is evidence to suggest that a surveillance approach can be considered since there are no significant radiological changes observed in lesions during long-term follow-up. However, other studies have suggested loco-regional spread can be present in ≤2 cm pNETs. The aim of this study was to characterise the prevalence of malignant features and identify any useful predictive variables in a surgically resected cohort of pNETs. 418 patients with pNETs were identified from 5 NET centres. Of these 227 were included for main analysis of tumour characteristics. Mean age of patients was 57 years, 47% were female. The median follow-up was 48.2 months. Malignant features were identified in 38% of ≤2 cm pNETs. ROC analysis showed that the current cut-off of 20 mm had a sensitivity of 84% for malignancy. The rate of malignant features is in keeping with other surgical series and challenges the belief that small pNETs have a low malignant potential. This study does not support a 20 mm size cut-off as being a solitary safe parameter to exclude malignancy in pNETs.
Utility of chromogranin A, pancreatic polypeptide, glucagon and gastrin in the diagnosis and follow-up of pancreatic neuroendocrine tumours in multiple endocrine neoplasia type 1 patients