PURPOSE: A comprehensive analysis was performed for five histologic types of appendiceal tumors to compare incidence, clinicopathologic features, survival, and appropriateness of surgery. METHODS: All patients diagnosed with mucinous adenocarcinoma (n = 951), adenocarcinoma (n = 646), carcinoid (n = 435), goblet (n = 369), and signet-ring cell (n = 113) in the Surveillance, Epidemiology, and End Results database (1973-2001) were analyzed. Evaluation of incidence, stage, and five-year relative survival were determined for each histology. The appropriateness of the operative procedure (i.e., appendectomy vs. colectomy) was examined by tumor type and size. RESULTS: Tumor incidence, patient demographics, survival outcomes, and appropriateness of surgery varied significantly among the different appendiceal tumor histologies. The most common appendiceal tumors were mucinous. With regard to patient demographics, carcinoids presented at an earlier mean age of 41 years and 71 percent were female (P < 0.001 for both). Overall five-year survival was highest for carcinoid (83 percent) and lowest for signet ring (18 percent). Although current guidelines specify that a right hemicolectomy (rather than an appendectomy) be performed for all noncarcinoid tumors and carcinoid tumors >2 cm, we found that 30 percent of noncarcinoids underwent appendectomy. Similarly, 28 percent of carcinoids >2 cm underwent appendectomy, which is a lesser resection than is indicated. CONCLUSIONS: This study provides a population-based analysis of epidemiology, tumor characteristics, survival, and quality of care for appendiceal carcinomas. This characterization provides a novel description of the presentation and outcomes for malignancies of the appendix and highlights that a substantial number of patients with appendiceal tumors may not be receiving appropriate surgical resection. METHODS: All patients diagnosed with mucinous adenocarcinoma (n = 951), adenocarcinoma (n = 646), carcinoid (n = 435), goblet (n = 369), and signet-ring cell (n = 113) in the Surveillance, Epidemiology, and End Results database (1973-2001) The appropriateness of the operative procedure (ie, appendectomy vs. colectomy) was examined by tumor type and size. RESULTS: Tumor incidence, patient demographics, survival outcomes, and appropriateness of surgery similarly significantly among the The most common appendiceal tumors were mucinous. With regard to patient demographics, carcinoids presented at an earlier mean age of 41 years and 71 percent were femal Overall five-year survival was highest for carcinoid (83 percent) and lowest for signet ring (18 percent). Although current guidelines specify that a right hemicolectomy (rather than an appendectomy) be performed for all Noncancerous tumors and carcinoid tumors> 2 cm, we found that 30 percent of noncarcinoids underwent appendectomy. Similarly, 28 percent of carcinoids> 2 cm underwent appendectomy, which is a lesser resection than indicated. CONCLUSIONS: This study provides a population-based analysis of epidemiology, tumor characteristics, survival, and quality of care for appendiceal carcinomas. This characterization provides a novel description of the presentation and outcomes for malignancies of the appendix and highlights that a substantial number of patients with appendiceal tumors may not be appropriate appropriate resection .