Neuroendocrine cancers are an uncommon form of cancer that arise specifically in neurons which produce hormones. These sorts of neurons are found most often in the digestive system or the adrenal glands. Neuroendocrine tumours are often small and difficult to detect with conventional imaging such as CT or MRI, and it can be tricky to biopsy them, because disturbing the tissue can sometimes cause a large release of hormones. A new PET tracer, uPAR, is able to detect the functional activity of these tumours, allowing them to be more easily diagnosed and therefore referred for better treatment earlier. It can also aid physicians in determining who is at greater risk of disease progression.