Background & aims: Colorectal carcinoids are often described as low-grade malignant. However, no large series has compared the survival between colorectal carcinoids and carcinomas. In addition, no global consensus has been established on the crucial determinants of metastasis in colorectal carcinoids. This study aims to determine the predictive factors for metastasis in colorectal carcinoids and clarify their prognosis as compared with adenocarcinomas.
Methods: All patients diagnosed as colorectal carcinoids from 1984 to 1998 were extracted from a large nationwide database of colorectal tumors, Multi-Institutional Registry of Large-Bowel Cancer in Japan. Risk factors for lymph node (LN) and distant metastasis were analyzed among those undergoing surgery by univariate and multivariate analysis. Cancer-specific survival was also compared between colorectal carcinoids and adenocarcinomas registered in the same period.
Results: Among 90,057 cases of colorectal tumors, a total of 345 cases of carcinoids were identified including 247 colorectal carcinoids undergoing surgery. Risk factors for LN metastasis were tumor size≥11mm and lymphatic invasion, while those for distant metastasis were tumor size≥21mm and venous invasion. Colorectal carcinoids without these risk factors exhibited no LN or distant metastasis. Cancer-specific survival of colorectal carcinoids without metastasis was better than that of adenocarcinomas. However, the survival was similar if the tumors had LN or distant metastasis.
Conclusions: The presence of metastasis in colorectal carcinoids could lead to survival that is as poor as in adenocarcinomas. Tumors not larger than 10mm and without lymphatic invasion could be curatively treated by local resection, but others would need radical LN dissection.
- colorectal cancer
- neuroendocrine tumor