WASHINGTON, D.C. / RankWire.AI / – Patients who had their appendix removed due to acute appendicitis showed a lower rate of later colorectal cancer diagnoses compared to similar individuals treated solely with antibiotics. Researchers analyzed matched patient groups within a large international health database. Among these, 0.7% of patients who underwent an appendectomy developed colorectal cancer, whereas 1.7% of those treated with antibiotics alone did. This difference indicated a 58% lower relative risk for patients who had surgery. The results reveal an association, but do not establish that appendectomy directly prevents colorectal cancer.
The study utilized the TriNetX Global Collaborative Network, which encompasses records from 168 healthcare organizations. Researchers identified individuals with acute appendicitis who received either surgical intervention or antibiotics. Matching procedures created two initial cohorts of 15,774 patients each. After removing those with prior colorectal cancer diagnoses, the analysis focused on 15,616 surgical patients and 15,295 antibiotic-treated patients. Within these groups, 110 cases of colorectal cancer occurred in the appendectomy group and 254 cases among those treated only with antibiotics.
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 but has not yet undergone peer review in a medical journal. This status remains crucial when evaluating the findings. The researchers did not claim that removing the appendix directly reduces cancer risk, nor did the study test appendectomy as a preventive measure for colorectal cancer.
Research investigates treatment options following appendicitis
Acute appendicitis occurs when the appendix becomes inflamed, often requiring urgent medical intervention. Surgeons typically remove the appendix surgically, though antibiotics can sometimes treat uncomplicated cases. These two treatment strategies formed the basis of comparison in the recent study. Valentine Nfonsam from Morehouse School of Medicine served as the senior author. He emphasized that antibiotic therapy remains a key 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 might influence the link between appendicitis and colorectal cancer. In certain patients, an undiagnosed tumor on the right side of the colon could cause inflammation of the appendix. Surgical removal allows tissue to be examined by a pathologist, which may uncover abnormalities and lead to further testing. Patients treated solely with antibiotics do not undergo tissue examination at the time of treatment, creating a significant difference in the potential detection of underlying disease.
Findings do not definitively prove a protective effect against cancer
The appendix contains immune-related tissue and plays a role in the gut environment. Scientists have also explored its connection with the gut microbiome, which includes microorganisms residing in the digestive system. The current analysis did not determine whether these biological features explain the differences in colorectal cancer diagnoses. Researchers also did not establish inflammation, microbiome alterations, or immune activity as causes for the observed association. Therefore, the study indicates a correlation between treatment type and diagnosis rates, but does not confirm that surgery offers protection against colorectal cancer.
Earlier studies have reached varying 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 and found no evidence that appendectomy increased long-term colorectal cancer or precursor risk. The current research narrows the focus to comparing patients treated surgically for acute appendicitis with matched individuals receiving only antibiotics. It is important to note that established risk factors for colorectal cancer include age, family history, and inherited genetic traits.