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Prognosis and risk factors of metastasis in colorectal carcinoids: results of a nationwide registry over 15 years
  1. Tsuyoshi Konishi1,
  2. Toshiaki Watanabe3,
  3. Junji Kishimoto4,
  4. Kenjiro Kotake5,
  5. Tetsuichiro Muto5,
  6. Hirokazu Nagawa2,
  7. on behalf of the Japanese Society for Cancer of the Colon and Rectum
  1. 1Department of Surgical Oncology, University of Tokyo, Tokyo, Japan
  2. 2Department of Surgery, Teikyo University School of Medicine, Tokyo, Japan
  3. 3Digital Medicine Initiative, Kyusyu University, Fukuoka, Japan
  4. 4Department of Surgery, Tochigi Cancer Center, Tochigi, Japan
  5. 5Department of Surgery, Cancer Institute Hospital, Tokyo, Japan
  1. Correspondence to:
    Dr T Watanabe
    Department of Surgery, Teikyo University School of Medicine, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan; toshwatanabe{at}


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.

Aim: 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.

  • JSCCR, Japanese Society for Cancer of the Colon and Rectum
  • LN, lymph node
  • WHO, World Health Organization

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  • Published Online First 9 January 2007

  • Funding: This study was supported in part by a grant-in-aid for cancer research from the Ministry of Health, Labour and Welfare of Japan, and from the Ministry of Education, Science, Sports, Culture and Technology of Japan.

  • Competing interests: None.

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