Key Takeaways
In a matched cohort of more than 30,000 appendicitis patients, appendectomy was associated with a 58% lower relative risk of a later colorectal cancer diagnosis (0.7% vs. 1.7%).
Age, family history, genetic predisposition, and other established colorectal cancer risk factors may ultimately help inform patient selection and follow-up.
Exact mechanisms behind the association are unknown, but could be tied to earlier detection of an underlying cancer, removal of a source of inflammation, and the appendix’s potential role in the intestinal microbiome and immune system.
The findings will be presented at the American College of Surgeons Clinical Congress 2026 in Washington, Sept. 26-29.
WASHINGTON (September 25, 2026) — Patients who underwent an appendectomy for acute appendicitis had a significantly lower subsequent risk of colorectal cancer than similar patients treated with antibiotics alone, according to new research.
The research will be presented at the American College of Surgeons (ACS) Clinical Congress 2026 in Washington, Sept. 26-29, where thousands of surgeons will convene to advance surgical quality, patient safety, and access to care.
Appendicitis is inflammation of the appendix, a small, narrow organ located near the junction of the small and large intestines. The removal of the appendix, or appendectomy, is one of the most common surgeries in the United States. In select patients, appendicitis can also be managed with antibiotics rather than surgery.
“The management of acute appendicitis has changed significantly over the last decade, and antibiotic therapy is now an accepted option,” said senior author Valentine Nfonsam, MD, MS, FACS, FASCRS, professor and executive vice chair of the department of surgery at Morehouse School of Medicine. “However, most of the discussion has focused on short-term outcomes: avoiding surgery, recurrence, complications, and quality of life. We wanted to ask a different question: Are there potential long-term oncologic implications of leaving the appendix in place after appendicitis?”
Researchers performed a retrospective cohort study using the TriNetX Global Collaborative Network, which included data from 168 health care organizations. The investigators identified patients diagnosed with acute appendicitis who were treated with either an appendectomy or antibiotics alone.
After matching the groups by characteristics, each treatment group included 15,774 patients. Once patients with a colorectal cancer diagnosis before the study’s outcome period were excluded, there were 15,616 appendectomy patients and 15,295 patients treated with antibiotics.
Using retrospective data, the researchers found that colorectal cancer was diagnosed in 110 patients who underwent appendectomy, or 0.7%, compared with 254 patients treated with antibiotics alone, or 1.7%. Appendectomy was associated with a 58% lower relative risk of a subsequent colorectal cancer diagnosis.
“These results should not be interpreted to mean that everyone with appendicitis needs an appendectomy to prevent cancer,” Dr. Nfonsam said. “Antibiotic management remains an important option. But when we discuss nonoperative management, we should also think beyond the immediate episode of appendicitis and consider potential long-term oncologic risk and appropriate monitoring.”
“Useless” Organ or Small but Mighty?
The appendix was once widely viewed as a useless organ, simply a leftover from evolution. Emerging research, however, suggests that it may play a role in the intestinal immune system and the gut microbiome , the community of bacteria and other microorganisms living in the digestive tract.
According to Dr. Nfonsam, the appendix contains a substantial amount of lymphoid tissue that is thought to contribute to immune system functioning. Changes in inflammation and the microbial environment have been linked to processes involved in colorectal cancer, so the appendix’s biological functions represent one possible area for further investigation.
The authors say that an inflamed appendix could be a symptom of a larger problem in the digestive system, such as colorectal cancer. Removing the appendix gives surgeons a chance to examine the health of the digestive system directly and eliminates a source of inflammation.
“The appendix is more than a vestigial organ,” said Dr. Nfonsam. “It is rich in lymphoid tissue and participates in the intestinal microbiome and immune system in that area. Whether persistent inflammation or changes in the local microbial environment contribute to the development of cancer is biologically plausible, but our study cannot answer that question.”
In some patients, appendicitis may be an early sign of an undiagnosed colorectal cancer rather than a cause of a future cancer. For example, an occult right-sided colorectal tumor may obstruct drainage from the appendix and initially present as acute appendicitis.
Appendectomy also allows the removed appendix to undergo pathologic examination. Findings from that examination may prompt additional diagnostic testing. Patients treated with antibiotics alone do not have the same immediate opportunity for tissue analysis.
“Treatment should not be one size fits all,” Dr. Nfonsam said. “Age, genetic predisposition, family history, and other colorectal cancer risk factors may all be relevant as we study how to select patients and plan follow-up.”
Co-authors are Meghana Akula, BS; Syed Fahad Gillani, MD; Miriannie Rivera Valerio, MD, MS; Ahmad Zeineddin, MD; Cassie Bowers, BS; Miriam Michael, MD; Quyen D. Chu, MD, MBA, FACS; Christine E. Nembhard, MD, FACS; and May C. Tee, MD, MPH, FACS.
Disclosures: Authors have no disclosures to report.
Citation: Akula M, et al. Risk of Colorectal Cancer Following Appendectomy . Scientific Forum, American College of Surgeons (ACS) Clinical Congress 2026.
Note: Research abstracts presented at the ACS Clinical Congress Scientific Forum are reviewed and selected by a program committee but are not yet peer reviewed.
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The American College of Surgeons is a scientific and educational organization of surgeons that was founded in 1913 to raise the standards of surgical practice and improve the quality of care for all surgical patients. The College is dedicated to the ethical and competent practice of surgery. Its achievements have significantly influenced the course of scientific surgery in America and have established it as an important advocate for all surgical patients. The College has approximately 95,000 members and is the largest organization of surgeons in the world. "FACS" designates that a surgeon is a Fellow of the American College of Surgeons.
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Risk of Colorectal Cancer Following Appendectomy
25-Sep-2026