The answers below stem from the review of over 13,000 carcinoid cases covering five decades published in 2003, authored by Irvin Modlin and collegues.
What is the most common site of carcinoid in the human body? primary site is small intestine
What is the most common site of malignant carcinoid in body? primary site is small intestine
What is the most common site of carcinoid in gut? primary site is terminal ileum
What is the most common site of malignant carcinoid in gut? primary site is terminal ileum
Also, the most common sites of regional spread for all carcinoids are lymph nodes and the most common site for distant spread for all carcinoids is the liver.
Reference: See Dr. Modlin’s article A 5-Decade Analysis of 13,715 Carcinoid Tumors (Full text PDF)
By Irvin M. Modlin, M.D., Kevin D. Lys, M.D., Mark Kidd, Ph.D.
Cancer 2003 Feb 15;97(4):934-59
