WASHINGTON, D.C. / RankWire.AI / – Patients who had their appendix removed due to acute appendicitis showed fewer later diagnoses of colorectal cancer compared to similar individuals treated solely with antibiotics. Researchers analyzed matched patient groups within a large global health database. The study found that 0.7% of patients who underwent an appendectomy developed colorectal cancer, versus 1.7% of those treated with antibiotics alone. This reflected a 58% lower relative risk for the surgical group. It is important to note that these results indicate an association, not proof that appendectomy prevents colorectal cancer.
The investigation utilized the TriNetX Global Collaborative Network, which encompasses data from 168 healthcare organizations. Researchers identified individuals with acute appendicitis who received either surgery or antibiotics. After matching, two groups of 15,774 patients each were formed. Excluding those with prior colorectal cancer diagnoses, the final analysis involved 15,616 surgical patients and 15,295 patients treated with antibiotics. In this cohort, there were 110 colorectal cancer cases in the appendectomy group and 254 in the antibiotic-only group.
The study was presented by the American College of Surgeons during its 2026 Clinical Congress in Washington, from September 26 to 29. It was included in the Scientific Forum program after review for conference presentation but has not undergone peer review in a medical journal. This status is significant when interpreting the findings. The researchers did not claim that removing the appendix directly reduces cancer risk, nor did the study test appendectomy specifically as a preventive measure for colorectal cancer.
Analysis explores treatment choices following appendicitis
Acute appendicitis involves inflammation of the appendix, often requiring urgent intervention. Typically, the condition is treated with surgical removal, although antibiotics can be effective for uncomplicated cases. These two approaches formed the basis of comparison in this research. Valentine Nfonsam from Morehouse School of Medicine served as the senior author. He emphasized that antibiotic therapy remains a valuable option for suitable patients, despite the lower rate of subsequent colorectal cancer diagnoses observed in the surgical group.
The researchers also examined clinical factors that could influence the link between appendicitis and colorectal cancer. In some cases, an undiagnosed tumor in the right colon may cause inflammation of the appendix. Surgical removal allows for tissue examination by a pathologist, which can detect abnormalities and lead to further testing. Patients treated solely with antibiotics do not have tissue samples analyzed at the time of treatment, creating a notable difference in how potential disease is identified.
Findings do not confirm a protective effect against cancer
The appendix contains immune-related tissue and plays a role in the gut environment. Its connection to the gut microbiome, comprising microorganisms in the digestive system, has also been studied. However, the current analysis did not clarify whether these biological features explain the difference in colorectal cancer diagnoses. The researchers did not establish inflammation, microbiome alterations, or immune responses as causes of the observed association. Therefore, the study indicates a correlation between treatment type and diagnosis rates rather than a definitive protective effect from surgery.
Earlier research has yielded varied conclusions regarding appendectomy and long-term colorectal cancer risk. A 2024 prospective study tracked over 224,000 participants across three major cohorts for up to 32 years, finding no evidence that appendectomy increased long-term colorectal cancer risk or precursor conditions. This new research narrows the focus by comparing patients treated surgically for acute appendicitis with matched patients receiving only antibiotics. Known risk factors for colorectal cancer include age, family history, and genetic predispositions.