This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Surgery
Which of the following is true about gastrointestinal carcinoid tumor? 
Select and explain. 
A. Alcohol has no effect on the flushing attacks, B. Occur most commonly in jejunum, C. Tumors most commonly produce histamine, D. Preoperative octreotide scanning can detect extent of the disease
D: Preoperative octreotide scanning can detect extent of the disease
Answer: D: Preoperative octreotide scanning can detect extent of the disease 
Explanation: Answer- D. Preoperative octreotide scanning can detect extent of the diseaseThese neuroendocrine tumours occur throughout the gastrointestinal tract, most commonly in the appendix, ileum and rectum in decreasing order of frequency. Appendicular carcinoid tumours are most commonly noted as an incidental finding at appendicectomy.Carcinoid tumours arise from Kulchitsky cells at the base of intestinal crypts (of Lieberkuhn)The tumours can produce a number of vasoactive peptides, most commonly S-hydroxytryptamine (serotonin), but also histamine, prostaglandins and kallikrein.Classically, the flushing attack are induced by alcohol.The extent of disease can be assessed preoperatively using octreotide scanning, which may detect otheise clinically apparent primary and secondary tumour.