Circulating tumour cells (CTCs) are detectable in the blood in around 50% of patients with functioning NeuroEndocrine Tumours (NET) arising in the midgut area (tumours which are secreting hormones and are located in the area in the middle of the digestive system) and their presence usually means that the prognosis for the patient is poor. CTCs have also been shown to be valuable as predictive markers following treatment and there is increasing interest in using CTCs as ‘liquid biopsies’ that can help to inform treatment decisions. CTC analysis has the benefit of being relatively non- invasive and quick compared with a conventional CT scan and is therefore an attractive method of monitoring the tumour throughout the treatment period. The purpose of this study is to assess the clinical value that enumeration will have in predicting the clinical symptomatic response and progression free survival in patients receiving Somatuline Autogel for functioning midgut NETs over a one year period.