Glossary:
Cumulative incidence: total new cases.
Standardized incidence ratios: compare disease rates.
Pseudomyxoma peritonei: rare abdominal tumor.
Fine and Gray methods: analyze survival with competing risks.
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Article
Second Cancer Risk Heightened After Appendiceal Adenocarcinoma Diagnosis
Key Takeaways
- Patients with appendiceal adenocarcinoma have a 7.5% risk of second primary cancer within 10 years.
- There is a 12% excess incidence of secondary primary cancers, particularly colorectal, in these patients.
Adults with primary primary appendiceal adenocarcinoma face a higher risk of developing a second primary cancer, including colorectal and prostate cancers.
Adults with appendiceal adenocarcinoma have a higher risk of developing a second primary cancer, including colorectal and prostate cancers.
Among adult patients in the United States diagnosed with a first primary appendiceal adenocarcinoma, researchers found that one in every 13 will be diagnosed with a second primary cancer within 10 years.
The study, presented at the 2025 Gastrointestinal Cancers Symposium, also revealed that patients with appendiceal adenocarcinoma have an additional 12% excess incidence in secondary primary cancers and double the excess incidence in secondary primary colorectal cancers compared with the general population.
Furthermore, the study underscores the importance of implementing robust cancer prevention and early detection strategies for individuals diagnosed with appendiceal adenocarcinoma. These strategies, which include interventions such as colonoscopy screening and genetic testing, are identified as a critical clinical priority, according to the study.
“Incidence rates of rare appendiceal cancers are increasing across the United States. Although this is suggestive of a growing population of appendiceal cancer survivors over time, the risk of second primary cancers specific to patients with a first primary appendiceal adenocarcinoma remains unknown,” Dr. Andreana N Holowatyj, an assistant professor of medicine in the Division of Epidemiology and Cancer Biology at Vanderbilt University Medical Center and Vanderbilt-Ingram Cancer Center, in Nashville, Tennessee, and co-authors wrote in the abstract of their presentation.
Holowatyj also serves as research director and co-director of the Research Immersion Course at the Vanderbilt University School of Medicine.
The cumulative incidence of second primary cancer was 7.5% and 11.7, at 10 and 20 years after appendiceal adenocarcinoma diagnosis, respectively. The cumulative incidence was significantly different between sexes and age at the diagnosis of appendiceal adenocarcinoma.
For instance, at a 10-year post-diagnosis, the cumulative incidence of second primary cancer for females was 6.4% and for males was 8.8%. The overall standardized incidence ratios (SIRs) for any second primary cancer were 1.12, which as the study states, corresponds to an excess of 14.8 cancers per 10,000 person-years. SIRs for common types of second primary cancers included: 1.07 for prostate cancer, 2.12 for colorectal cancer, 0.91 for female breast cancer, 0.81 for lung cancer and 1.2 for melanoma.
During the trial, a total of 5,827 adults diagnosed with a first primary appendiceal adenocarcinoma (mean age 58 years) were identified during the trial period. Of those identified, 418 developed a second primary cancer (51.8% female). The most common types of second primary cancer were prostate cancer (17.7%), colorectal cancer (14.4%), female breast cancer (10.5%), lung cancer (8.4%) and melanoma (6%).
Appendiceal cancer originates in the appendix, a small pouch in the abdomen, with two main types: epithelial and neuroendocrine. Epithelial cancers may produce mucin, causing pseudomyxoma peritonei, while neuroendocrine tumors arise from enterochromaffin cells. Cancer may spread within the abdomen or, less commonly, through lymph nodes to other areas.
A population-based study was conducted using data from the Surveillance, Epidemiology, and End Results (SEER) Program, evaluating adults (18 or more years) diagnosed with first primary appendiceal adenocarcinoma from 1992 to 2021. Cumulative incidence of second primary cancer, defined as any primary cancer occurring three or more months after appendiceal adenocarcinoma, was estimated using Fine and Gray methods to account for the competing risk of death. SIRs were calculated to compare the observed number of second cancers with the expected number, based on age-, sex- and race-specific incidence rates in the general population.
References:
- “Risk of second primary cancer among patients with a first primary appendiceal adenocarcinoma.” By Dr. Holowatyj AN, et al, Presented at: 2025 Gastrointestinal Cancers Symposium; 2025 Jan 16-18; San Francisco, CA. Abstract 819
- “Appendiceal cancer (rare digestive system tumors).” National Cancer Institute. Pediatric and Adult Rare Tumor Network.
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