What Are the Consequences? Carcinoid Tumors to the Liver
Carcinoid tumors are generally considered less aggressive tumors than adenocarcinomas arising in the same locations. However, site of origin of the tumor makes a difference in appearance of symptoms, in incidence of metastases, and in estimation of survival. Foregut carcinoids, those arising in the stomach and in the duodenum, are metastatic to lymph nodes or to the liver at the time of diagnosis about half of the time. Of the patients with liver metastases, patients with primary tumors arising from the stomach exhibit the carcinoid syndrome up to one third of the time while these symptoms are rare in those with duodenal carcinoids. Twenty percent of these patients with liver metastases will survive at least ten years. Hindgut carcinoids, which arise from the colon and rectum, differ in metastatic rate at diagnosis. While colon carcinoids, which are rare, are found to be metastatic half of the time, rectal carcinoids are metastatic at diagnosis in only one-fifth of cases. Only rarely does either type of hindgut carcinoid tumors cause the carcinoid syndrome when metastatic to the liver. These metastatic patients with primary tumors of hindgut origin have similar survival characteristics to foregut patients in that twenty percent of patients survive ten years. In contrast, patients with midgut tumors (arising from the jejunum, the ileum, the appendix, and the cecum) metastatic to the liver have significantly better survival rates, with thirty percent living at least ten years. However, these patients are more often symptomatic, with up to forty percent complaining of symptoms of the carcinoid syndrome. Also, because these sites are less readily imaged or visualized endoscopically, these patients have metastatic disease at diagnosis the majority of the time.
