Colon carcinoid tumors. A population-based study.
PURPOSE: The aim of our investigation was to evaluate the clinical presentation of patients with carcinoid tumors of the colon and to estimate the survival and potential prognostic factors of this tumor type. METHODS: A population-based study was performed using data from the Alberta Cancer Registry between 1964 and 1988 (inclusive). The clinical records and the pathologic material of eligible patients were reviewed. Survival was estimated both as crude survival and with the Kaplan-Meier method. RESULTS: During the 25-year study period (1964-1988), 36 true carcinoid tumors of the colon were diagnosed in Alberta. Carcinoids of the ileocecal region and of the rectum were excluded from the study. The average age at time of diagnosis was 68.4 years; there were 20 males and 16 females. Symptoms (abdominal pain, diarrhea, weakness, anorexia) occurred late in the course of the disease: 64 percent of the lesions were in Dukes D stage and 22 percent were Dukes C at diagnosis. Only one patient presented with a malignant carcinoid syndrome. Lesions occurred most frequently in the cecum (39 percent), followed by transverse and sigmoid colon. Most of the patients were managed surgically. The perioperative mortality rate was with 22 percent, which is quite high. The average size of the lesions was 5.8 (range, 2-10) cm, and most tumors (31/36) had invaded the pericolic fat. The most common immunohistochemical pattern was argentaffin/argyrophil negative and neuron-specific enolase positive. Two-year and five-year actuarial (Kaplan-Meier) survival was 34 percent and 26 percent, respectively. Survival for carcinoids of the colon was significantly lower compared with carcinoids of the rectum or appendix, and with colon adenocarcinomas. Size of the tumor and tumor invasion into the muscularis propria--the two major histopathologic prognostic factors for carcinoids of the gastrointestinal tract--were not found to influence survival significantly. Rather, tumor stage, histologic pattern, tumor differentiation, nuclear grade, and mitotic rate were found to significantly influence the survival rate. CONCLUSION: Carcinoid tumors of the colon are extremely rare tumors, diagnosed late in the course of the disease, and they carry a bad prognosis. Prognostic factors are tumor stage, histologic pattern, differentiation, nuclear grade, and mitotic rate of the tumor.