MONDAY, Sept. 14, 2026 (HealthDay News) — Many people afflicted by rare appendix cancers may not need post-surgical chemotherapy, new research shows.
In most cases, such treatment won't prevent tumor recurrence or extend patient survival, according to a study of hundreds of cases.
A case-by-case approach might work best, concluded study senior author Dr. John Paul Shen, a research fellow of gastrointestinal medical oncology at MD Anderson Cancer Center in Houston.
"Our findings demonstrate that appendix cancer has a distinct biology and that, for most patients with localized disease, the risk of relapse is low," he said in a news release. "Understanding each tumor's unique characteristics can help us better identify who may benefit from closer monitoring while avoiding unnecessary treatment for others."
The findings were published Sept. 9 in JAMA Surgery.
The U.S. National Cancer Institute reports that appendiceal cancer is extremely rare, affecting only about 1 or 2 in 1 million people. But recent studies suggest it is becoming more common.
Until now, oncologists have typically assumed that cancers in the appendix follow patterns similar to colon cancer, and have treated them accordingly. That means following up appendix removal with chemotherapy.
But is this really the best approach?
The new study tracked outcomes among 202 patients with stage 1 to 3 cancers of the appendix. All underwent cancer surgery at MD Anderson between 2000 and 2024.
A minority (9.4%, or 19 patients) experienced tumor recurrence, and this was most likely among those with stage 3 disease.
While 95.7% of patients without a recurrence survived for five years after their diagnosis, only 77.2% of those who had a recurrence did so.
Receiving chemotherapy after surgery was not associated with cancer recurrence or survival, however.
Instead, the presence of key gene mutations in tumors appeared to affect the risk for cancer's return, Shen's group found. Various mutations played different roles in the odds for recurrence, based on the subset of tumor a patient had.
"Appendiceal cancers are not all the same," explained lead author Dr. Sacha El Khoury, another research fellow in gastrointestinal medical oncology at the cancer center.
"When we consider tumor histology [cellular makeup], together with its molecular features, we can better identify which patients are truly at a higher risk of recurrence," she said in the news release. "That's where tailoring treatment for this disease has to start.”
The bottom line, according to the Houston team, is that genetic testing may be needed to determine which patients can safely skip post-op chemotherapy, and which cannot.
The authors also stressed that because the study was done at just one center, more research is needed.
More information
Find out more about appendiceal cancer at the Mayo Clinic.
SOURCES: University of Texas M. D. Anderson Cancer Center, news release, Sept 9, 2026; U.S. National Cancer Institute
Copyright © 2026 HealthDay. All rights reserved.