The Rise in Appendiceal Cancer Incidence: 2000-2009

Appendiceal cancer 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. Using the Surveillance, Epidemiology, and End Results database, we conducted a retrospective cohort analysis of patients treated from 2000-2009. We identified 4765 patients with appendiceal cancer. The incidence of appendiceal cancer increased by 54 % from 2000 (0.63 per 100,000) to 2009 (0.97 per 100,000 population). Incidence rates increased across all tumor types, stages, age groups, and gender. The most common malignancies were mucinous adenocarcinoma (38 %), followed by carcinoids (28 %), adenocarcinoma-not otherwise specified (NOS) (27 %), and signet ring cell adenocarcinoma (7 %). Larger tumor size and older patient age were significantly associated with higher relative odds of distant disease at diagnosis (P < 0.0001). Patient and demographic characteristics were significantly associated with higher relative hazard of death (P < 0.0001). Although appendiceal cancer is rare, the incidence increased significantly in the USA from 2000 to 2009. The cause of this trend is not obvious. We did not observe increases differentially associated with stage, histology, or demographic characteristics. Further investigation is needed to examine factors underlying this increase.