3620 Background: No global consensus has been established on the crucial determinants of metastasis in colorectal carcinoids. This study aims to determine the predictive factors for lymph node (LN) and distant metastasis, and to provide strategic model for the treatment of this uncommon disease.
METHODS
All patients diagnosed as carcinoids from 1984 to 1998 were extracted from the nationwide database, "Multi-Institutional Registry of Large-Bowel Cancer in Japan", which covers almost 10% of all colorectal cancers in Japan. Risk factors for metastasis were analyzed among colorectal carcinoids undergoing surgery.
RESULTS
Among 90,057 cases of colorectal tumors registered from 1984 to 1998, a total of 345 cases of carciniods were identified. All cases were from the Asian population. The site distribution consisted of the ileum 3 (0.9%), appendix 8 (2.3%), colon 28 (8.2%) and rectum 304 (88.6%). Among colorectal carcinoids, a total of 263 cases undergoing surgery were eligible for the analysis (colon 23, rectum 240). Overall incidence of LN and distant metastasis were 29% and 7%, respectively. Univariate analysis showed that age>55, tumor size, tumor invasion≥T2, and lymphovascular invasion were associated with LN metastasis as well as distant metastasis. Multivariate analysis revealed that tumor size>10mm and lymphovascular invasion (LVI) were independently predictive of LN metastasis, while tumor size>20mm was a single risk factor for distant metastasis. Notably, tumors not larger than 10mm and without LVI exhibited no LN metastasis ( Table ).
CONCLUSIONS
Tumors not larger than 10mm and without LVI could be curatively treated by endoscopic resection or transanal excision. However, tumors larger than 10mm or those with LVI should undergo radical surgery for LN dissection. Furthermore, tumors larger than 20mm carry a high risk for distant metastasis, and require close follow-up even without evident metastasis at the time of surgery. [Table: see text] No significant financial relationships to disclose.