WASHINGTON, D.C. / RankWire.AI / – Patients who underwent appendix removal for acute appendicitis later recorded fewer colorectal cancer diagnoses than similar patients treated with antibiotics alone. Researchers compared matched patient groups in a large international health database. Colorectal cancer appeared in 0.7% of patients who had an appendectomy, compared with 1.7% of those who received antibiotics only. The difference represented a 58% lower relative risk among patients who underwent surgery. The findings show an association, not proof that appendectomy prevents colorectal cancer.
The research team utilized the TriNetX Global Collaborative Network, which incorporated records from 168 healthcare organizations. Investigators identified individuals with acute appendicitis who received either surgical intervention or antibiotics. Matching generated two initial cohorts of 15,774 patients each. After excluding patients with prior colorectal cancer diagnoses, researchers analyzed 15,616 surgical patients and 15,295 antibiotic-treated patients. They found 110 colorectal cancer cases in the appendectomy group and 254 cases among patients treated only with antibiotics.
The American College of Surgeons featured this research at its 2026 Clinical Congress in Washington, held from Sept. 26 through Sept. 29. The study was included in the Scientific Forum program following review for conference presentation. It has not undergone peer review in a medical journal. That status remains crucial when evaluating the results. Researchers did not conclude that removing the appendix directly reduces cancer risk, nor did the study test appendectomy as a preventative measure for colorectal cancer.
Analysis investigates treatment strategies following appendicitis
Acute appendicitis arises when the appendix becomes inflamed and often necessitates urgent medical intervention. Surgeons commonly remove the appendix via surgery, whereas antibiotics can be effective for certain uncomplicated cases. These two methods formed the basis of comparison in the new research. Valentine Nfonsam of Morehouse School of Medicine served as the senior author. He emphasized that antibiotic therapy remains an essential treatment choice for suitable patients, despite the lower rate of subsequent colorectal cancer diagnoses observed in the surgical group.
Researchers also examined clinical factors that could complicate the link between appendicitis and colorectal cancer. In some cases, an undetected tumor in the right side of the colon may contribute to inflammation of the appendix. Surgical removal allows for tissue examination by a pathologist, which can reveal abnormalities and prompt further diagnostic testing. Patients treated solely with antibiotics do not have that tissue examined at the time of treatment, creating a significant difference in the potential detection of underlying disease.
Findings do not establish a causal protective effect
The appendix contains immune-related tissue and is part of the intestinal environment. Scientists have also explored its connection with the gut microbiome, which encompasses microorganisms residing in the digestive tract. The current analysis did not determine whether these biological factors explain the difference in colorectal cancer diagnoses. Researchers also did not establish inflammation, microbiome alterations, or immune activity as causes of the observed association. Therefore, the study indicates a correlation between treatment method and diagnosis rates, not a definitive protective effect from appendectomy.
Previous studies have drawn varying conclusions regarding appendectomy and long-term colorectal cancer risk. A 2024 prospective study tracked over 224,000 participants across three major cohorts for as long as 32 years. That research found no evidence that appendectomy increased long-term colorectal cancer risk or colorectal precursor risk. The current study, however, focuses on a narrower question by comparing patients treated for acute appendicitis via surgery with those treated only with antibiotics. Key colorectal cancer risk factors such as age, family history, and genetic predispositions remain relevant.