HOUSTON, SEPTEMBER 9, 2026 ― Most patients with localized appendix cancer may be able to safely avoid chemotherapy after surgery, according to a new study from researchers at The University of Texas MD Anderson Cancer Center .
The study, published in JAMA Surgery , found that fewer than 10% of patients experienced recurrence after surgery, and chemotherapy given after surgery was not associated with improved survival or a lower risk of relapse, even among patients considered higher risk. Researchers also identified specific tumor characteristics and genomic alterations that may help doctors better predict which patients are most likely to see their cancer return.
This analysis, led by John Paul Shen, M.D. , associate professor of Gastrointestinal Medical Oncology , and Sacha El Khoury, M.D., a research fellow of Gastrointestinal Medical Oncology, represents the largest study to date of localized appendix cancer.
"For too long, the outdated notion that appendix cancer behaves similarly to colon cancer has driven treatment decisions for our patients," Shen said. "Our findings demonstrate that appendix cancer has a distinct biology and that, for most patients with localized disease, the risk of relapse is low. Understanding each tumor's unique characteristics can help us better identify who may benefit from closer monitoring while avoiding unnecessary treatment for others."
What are other key findings from the study?
The researchers reviewed outcomes for 439 patients with stage 1 to 3 appendix cancer treated at UT MD Anderson between 2000 and 2024. Of those, researchers evaluated cancer recurrence among 202 patients who underwent surgery.
Nineteen patients (9.4%) experienced recurrence during a median follow-up of more than five years. Recurrence occurred in 6% of patients with stage 2 disease and 19.5% of those with stage 3 disease.
Patients whose cancer returned had poorer outcomes, with a five-year overall survival rate of 77.2%, compared with 95.7% among those who did not experience recurrence.
How can genetic testing help identify patients at higher risk of recurrence?
Researchers found that certain genetic changes were associated with a higher risk of cancer returning. TP53 mutations were linked to recurrence in goblet cell tumors, while GNAS mutations were associated with higher relapse risk in non-goblet tumors.
"Appendiceal cancers are not all the same," El Khoury said. "When we consider tumor histology together with its molecular features, we can better identify which patients are truly at a higher risk of recurrence. That's where tailoring treatment for this disease has to start."
Why is this study important for patients?
Appendix cancer is rare, and doctors often rely on what they know about colorectal cancer to help guide treatment and follow-up care. This study suggests appendix cancer behaves differently and may need its own set of risk factors to predict whether the cancer will return.
By looking at the type of tumor and its genetic features, experts may be able to identify which patients are more likely to have their cancer return, while helping others avoid chemotherapy and its potential side effects.
Limitations of this study include that patients were treated at a single cancer center and therefore more research is needed to confirm the findings.
