Introduction
Appendiceal tumors are considered to be a relatively rare tumor of the gastrointestinal tract, and the prognosis is unclear. The development of the small intestine, colon, peritoneum, omentum, and mesentery as second primary malignancies (SPMs) following appendiceal tumors is rarely mentioned in the literature. No studies discussed the association between small intestine, colon, peritoneum, omentum, and mesentery SPMs and appendiceal cancer.
Aims & Methods
The purpose of this study was to evaluate the risk of small intestine, colon, peritoneum, omentum, and mesentery SPMs following appendiceal cancer .
The Surveillance Epidemiology and End Result (SEER) database was used to obtain data of patients diagnosed with appendiceal cancer from 1975 to 2022. We used the MP-SIR session with multiple outcome analysis, and the event was defined as small intestine, colon, peritoneum, omentum, and mesentery. Excess absolute risk (EAR) was measured per 10,000. The standardized incidence ratio (SIR) was computed as observed/expected (O/E) with a 95% confidence interval (CI).
Results
Among 7723 appendiceal cancer patients, SIRs for second primary malignancies were significantly elevated over all time intervals, with small intestine cancer having an O/E of 20.38 (P<0.05, EAR=8.37, 95% CI: 6.57–47.55) for 2–11 months, 11.58 (P<0.05, EAR=4.86, 95% CI: 5.54–21.30) for 12–59 months, 13.89 (P<0.05, EAR=6.90, 95% CI: 6.34–26.37) for 60–119 months, and 3.81 (P<0.05, EAR=1.84, 95% CI: 1.02–9.75) for ≥120 months, colon cancer with an O/E of 3.34 (P<0.05, EAR=13.58, 95% CI: 1.67–5.98) for 2–11 months, 2.31 (P<0.05, EAR=7.84, 95% CI: 1.51–3.38) for 12–59 months, and 1.99 (P<0.05, EAR=7.00, 95% CI: 1.16–3.19) for 60–119 months, and peritoneum, omentum, and mesentery malignancies with an O/E of 11.55 (P<0.05, EAR=0.97, 95% CI: 1.30–41.70) for 12–59 months, 15.69 (P<0.05, EAR=1.55, 95% CI: 1.76–56.66) for 60–119 months, and overall cumulative O/E values of 9.97 (P<0.05, EAR=4.97, 95% CI: 6.63–14.42) for small intestine, 1.77 (P<0.05, EAR=5.45, 95% CI: 1.37–2.25) for colon, and 6.41 (P<0.05, EAR=0.64, 95% CI: 1.72–16.40) for per.
Conclusion
Appendiceal cancer patients are at significantly higher risk for second primary malignancies, primarily involving the small intestine, colon, and peritoneal-associated sites. The risk is highest within the initial 10 years after diagnosis, supporting the need for scrupulous long-term follow-up in these individuals.
References
1- Surveillance, Epidemiology, and End Results (SEER) Program (www.seer.cancer.gov) SEER*Stat Database: Incidence - SEER Research Data, 8 Registries, Nov 2024 Sub (1975-2022), National Cancer Institute, DCCPS, Surveillance Research Program, released April 2025, based on the November 2024 submission
2- Wang D, Ge H, Lu Y, Gong X. Incidence trends and survival analysis of appendiceal tumors in the United States: Primarily changes in appendiceal neuroendocrine tumors. PLoS One. 2023 Nov 13;18(11):e0294153. doi: 10.1371/journal.pone.0294153IF: 2.9 Q1 . PMID: 37956190; PMCID: PMC10642837.