Elevated risk of subsequent malignancies in patients with appendiceal cancer: A population-based analysis

Background: Appendiceal cancer is extremely rare with excellent survival after curative resection. There is a concern for the development of additional cancers in survivors of appendiceal cancer. However, existing data is limited to small anecdotal reports on appendiceal carcinoid only. We aim to investigate the risk of subsequent malignancies in patients with appendiceal carcinoma and correlate the risk according to patient and clinical characteristics. Methods: We identified 3788 patients with appendiceal cancer from the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) database between 1992 and 2011. Standardized incidence ratios (SIRs) for the risk of additional cancers were calculated and quantified based on tumor site, gender, race, latency, primary tumor stage, and histology. Results: Three hundred and fifty-nine subsequent malignancies were identified in 313 patients (mean age 60 years, male to female ratio 1.3:1). The overall risk for a subsequent malignancy was elevated by 20 % compared with the general population. Most common sites with significantly increased risk for subsequent cancers included the small intestine (n=13) and the colon/rectum (n=48). Malignant carcinoid and adenocarcinoma were the dominant histological subtypes at these sites, respectively. Significant elevated risk was observed within the first 5 years of follow up in white males with either localized or regional disease. Adenocarcinomas and goblet cell carcinoid tumors of the appendix were associated with increased risk; whereas, the risk was significantly reduced in patients with malignant carcinoid tumors. Conclusion: There is an increased risk of subsequent cancers in patients with appendiceal carcinoma.