WASHINGTON, D.C. / RankWire.AI / – Patients who had their appendix removed due to acute appendicitis showed fewer diagnoses of colorectal cancer compared to similar individuals treated solely with antibiotics. Researchers analyzed matched patient groups within a large international health database. The data revealed that 0.7% of patients who underwent an appendectomy developed colorectal cancer, compared to 1.7% of those treated only with antibiotics. This difference indicates a 58% lower relative risk among the surgical group. It is important to note that these findings show an association, not definitive proof that appendectomy prevents colorectal cancer.
The study utilized the TriNetX Global Collaborative Network, which encompasses records from 168 healthcare organizations. Researchers identified individuals diagnosed with acute appendicitis who received either surgical treatment or antibiotics. After matching, two initial groups of 15,774 patients each were formed. Following the exclusion of patients with prior colorectal cancer diagnoses, the final analysis involved 15,616 surgical patients and 15,295 patients treated with antibiotics only. Among these, 110 cases of colorectal cancer were found in the appendectomy group, while 254 cases were identified among the antibiotic-only group.
The American College of Surgeons presented this research at its 2026 Clinical Congress in Washington, which took place from Sept. 26 to Sept. 29. The study was included in the Scientific Forum program after review for conference presentation, though it has not undergone peer review in a medical journal. This status is significant when evaluating the validity of the findings. The researchers emphasized that they did not conclude that removing the appendix directly reduces cancer risk, nor did the study test appendectomy as a preventive measure for colorectal cancer.
Investigation explores treatment options following appendicitis
Acute appendicitis occurs when the appendix becomes inflamed, often requiring urgent medical intervention. Typically, doctors remove the appendix surgically, but antibiotics can be used to treat selected uncomplicated cases. The comparison in this new research focused on these two approaches. Valentine Nfonsam of Morehouse School of Medicine served as the senior author. He noted that antibiotic therapy remains an essential treatment option for suitable patients, despite the lower rate of subsequent colorectal cancer diagnoses observed in the surgical group.
The study also considered clinical factors that could influence the link between appendicitis and colorectal cancer. In some cases, an undiagnosed tumor on the right side of the colon may cause inflammation of the appendix. Surgical removal allows pathologists to examine excised tissue, which can reveal abnormalities and lead to further testing. Patients treated only with antibiotics do not have this tissue examined at the time of treatment, which creates a meaningful difference in the potential detection of underlying disease.
Findings do not establish a causal protective effect
The appendix contains immune-related tissue and plays a role in the gut environment. Researchers have also explored its connection to the gut microbiome, which includes microorganisms inhabiting the digestive system. The current analysis did not determine whether these biological factors account for the variation in colorectal cancer diagnoses. Neither inflammation, microbiome alterations, nor immune activity was confirmed as causative factors for the observed association. Therefore, the study indicates a correlation between treatment type and subsequent diagnosis rates rather than establishing that surgery offers protection against cancer.
Previous studies have produced differing conclusions regarding appendectomy and long-term colorectal cancer risk. A 2024 prospective analysis tracked over 224,000 participants across three major cohorts for up to 32 years, finding no evidence that appendectomy increased long-term colorectal cancer or precursor risk. This new research narrows the focus to comparing patients treated surgically for acute appendicitis with those managed only with antibiotics. Known risk factors for colorectal cancer still include age, family history, and genetic predispositions.