When someone is diagnosed with a NET, or any other type of cancer,  it’s only natural to want answers. First and foremost, questions such as “What type of cancer do I have and where did it start?” will come to  mind. Unfortunately, the answers to these questions are not always straightforward.

Although most types of NETs can now be identified with the use of  advanced pathology techniques, a few types resist classification by site  of origin. Your healthcare team will do their best to identify and classify  your tumour, since certain NETs respond well to specific chemotherapy or other treatment options.

Generally, NETs of unknown primary origin occur within the following three broad categories:

• low-grade neuroendocrine carcinoma;
• small cell carcinoma;
• poorly differentiated neuroendocrine carcinoma

Each have its own unique characteristics.  If a cancer has spread to one or more locations throughout the body but the site where it originated remains unknown, it is called a cancer of unknown primary (CUP).