Types of neuroendocrine cancer are named according to where the tumour started in the body. They are also classified as functional or nonfunctional. Functional neuroendocrine tumours (NETs) make too much of a hormone and cause symptoms. Nonfunctional NETs may make hormones, but do not cause symptoms. 

Another way of classifying neuroendocrine cancer is as indolent or aggressive. Indolent NETs grow slowly, whereas aggressive NETs grow quickly and tend to spread to other parts of the body. 

Most types of neuroendocrine cancer are very rare. 

Types of neuroendocrine cancer include: 

• gastric NETs – start in the stomach 
• small bowel NETs 
• large bowel NETs 
• rectal NETs 
• pancreatic NETs 
• bronchopulmonary NETs – start in the lung 
• thymic NETs – start in the thymus 
• parathyroid cancer or adenoma 
• pituitary gland tumours 
• testicular NETs 
• ovarian and endometrial NETs 
• multiple endocrine neoplasia (MEN) – tumours form in more than one endocrine gland 
• pheochromocytoma – starts in the adrenal glands on top of the kidneys 
• paraganglioma – starts in nerve cell bundles called ganglia 
• medullary thyroid carcinoma – starts in the thyroid gland 
• adrenocortical carcinoma – starts in the adrenal glands 
• Merkel cell carcinoma – starts in the skin 
• neuroblastoma – starts in the adrenal glands, but can also occur in nerve tissues elsewhere in the body. 

Another way of classifying neuroendocrine cancer is as indolent or aggressive. Indolent NETs grow slowly, whereas aggressive NETs grow quickly and tend to spread to other parts of the body.