e12506 Background: Cancer of the appendix is a rare and potentially aggressive malignancy. The objectives of this study were to characterize secular demographic patterns of disease and to determine survival by using a population-based data source. Methods: Using the Surveillance Epidemiology and End Results database we identified all appendiceal neoplasms reported to the registry between 2000 and 2009.Tumors were classified as carcinoid, adenocarcinoma, mucinous and signet ring cell carcinoma. We compared overall incidence, age distribution by tumor type and overall survival rates by extent of disease at diagnosis. To assess whether the incidence rate, tumor size, and cancer stage changed over time, the Cochrane-Armitage trend test was used. Logistic regression models were used to determine the odds of distant disease at diagnosis and Cox proportional-hazards modeling was used to identify the factors associated with overall survival rates. Results: We identified 4,765 patients with appendix cancer. The incidence of appendiceal cancer increased by 54% from 2000 (0.63 per 100,000) to 2009 (0.97 per 100,000). Incidence rates increased across all tumor types, stages, age groups and gender. The most common malignancies were mucinous (38%), followed by carcinoids (28%) adenocarcinoma (27%), and signet ring cell carcinoma (7%). Distant stage at diagnosis was most common among, signet ring cell tumors (60%). Larger tumor size and older patient age were significantly associated with higher relative odds of distant disease at diagnosis (P < .0001). Tumor type, older age, black race, males, tumor size of 2 cm and greater, cancer stage and registry were significantly associated with higher relative hazard of death (P< .0001). Mean 5-year survival was 55% for carcinoid patients, 49% for adenocarcinoma, 50% for mucinous and 38% for the signet ring cell cohort. Conclusions: Although appendiceal cancer is rare, the incidence increased significantly in the U.S. from 2000 to 2009. The cause of this trend is not obvious. We did not see increases differentially associated with stage, histology, registry or demographic characteristics. Further investigation is needed to examine factors underlying this increase. This research was generously supported by the Betti Boers Maloney Appendix Cancer Research Fund at the University of Minnesota Foundation.