Trends in the Incidence, Prevalence, and Survival Outcomes of Appendiceal Adenocarcinoma

Abstract

Background: Appendiceal carcinoma is a rare malignant tumor with aggressive potentials. Appendiceal adenocarcinoma (AA) accounts for approximately two thirds of it. Aim: This study aimed to explore the epidemiologic changes of AA and reveal the possible influences of therapeutic advances on survival of patients with AA. Methods: We retrospectively identified 6066 patients with AA treated between 2000 and 2014 from the Surveillance, Epidemiology, and End Results (SEER) program. Pertinent data were analyzed for incidence and prevalence. Survival analysis was made by the actuarial or Kaplan-Meier and compared by log-rank test. Cox proportional hazards model was adopted for prognostic variable evaluation. Results: We identified 6066 cases with AA. Its annual age-adjusted incidence was 0.47 per 100,000 in 2000 and increased to 1.11 per 100,000 by 2014. The incidence increased the steepest in patients under 50 years old, with a threefold escalation to 0.60 per 100,000 in 2014. The elevation of the incidence was noted in all the histologic types, stages and grades. The 20-year limited-duration prevalence of AA was 6 per 100,000 on January 1, 2014. The multivariable analysis showed the median survival time was statistically different in gender, year of diagnosis, grade, stage, type of surgery performed and histologic subtype. The median survival time was prolonged from 2000-2006 to 2007-2014 (hazard ratio (HR) 0.87; 95% CI, 0.80-0.94). Conclusion: These results showed an elevation in the incidence, prevalence of AA, which may be interpreted by the advancement of examining techniques. The improvement in survival may result from the development of therapies. Furthermore, these results suggested clinicians pay more attention to AA and indicated some potential research directions.