title: Prognosis and risk factors of metastasis in colorectal carcinoids: results of a nationwide registry over 15 years.
abstract: BACKGROUND
  Colorectal carcinoids are often described as low-grade malignant. However, no study has compared the survival between patients with colorectal carcinoids and those with carcinomas, in a large series. In addition, no global consensus has been established on the crucial determinants of metastasis in colorectal carcinoids.
  
  
  OBJECTIVE
  To determine the predictive factors for metastasis in colorectal carcinoids and clarify their prognosis compared with adenocarcinomas.
  
  
  METHODS
  Data of all patients diagnosed as having colorectal carcinoids were extracted from a large nationwide database of colorectal tumours, the Multi-Institutional Registry of Large-Bowel Cancer in Japan, for the period from 1984 to 1998. Risk factors for lymph node (LN) metastases and distant metastases were analysed among those who were undergoing surgery, by univariate and multivariate analysis. Cancer-specific survival was also compared between patients with colorectal carcinoids and those with adenocarcinomas registered in the same period.
  
  
  RESULTS
  Among the 90 057 cases of colorectal tumours that were diagnosed, a total of 345 cases of carcinoids were identified, including 247 colorectal carcinoids of those undergoing surgery. Risk factors for LN metastasis were tumour size >/=11 mm and lymphatic invasion, whereas those for distant metastasis were tumour size >/=21 mm and venous invasion. Colorectal carcinoids without these risk factors exhibited no LN metastasis or distant metastasis. Cancer-specific survival of patients with colorectal carcinoids without metastasis was better than that of those with adenocarcinomas. However, the survival was similar between carcinoids and adenocarcinomas if the tumours had LN metastasis or distant metastasis.
  
  
  CONCLUSIONS
  The presence of metastasis in colorectal carcinoids could lead to survival that is as poor as in adenocarcinomas. Tumours </=10 mm and without lymphatic invasion could be curatively treated by local resection, but others would need radical LN dissection.
authors.affiliation: Department of Surgical Oncology, University of Tokyo, Tokyo, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Konishi
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Watanabe
authors.forename: Junji
authors.initials: J
authors.lastname: Kishimoto
authors.forename: Kenjiro
authors.initials: K
authors.lastname: Kotake
authors.forename: Tetsuichiro
authors.initials: T
authors.lastname: Muto
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Nagawa
mesh_terms: D000230:Adenocarcinoma / Q000401:mortality / Q000473:pathology / Q000556:secondary; D002276:Carcinoid Tumor / Q000401:mortality / Q000473:pathology / Q000556:secondary*; D015179:Colorectal Neoplasms / Q000401:mortality / Q000473:pathology*; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008207:Lymphatic Metastasis; D008297:Male; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D011379:Prognosis