WASHINGTON, D.C. / RankWire.AI / – Patients who had their appendix removed due to acute appendicitis showed fewer subsequent diagnoses of colorectal cancer compared to similar patients treated solely with antibiotics. Researchers analyzed matched patient groups within a large international health database. The data revealed that 0.7% of those who underwent an appendectomy developed colorectal cancer, whereas 1.7% of the antibiotic-only group did. This difference indicated a 58% lower relative risk for patients who received surgical removal. The results show an association, but do not prove that appendectomy prevents colorectal cancer.
The study utilized the TriNetX Global Collaborative Network, which compiles records from 168 healthcare organizations. Researchers identified individuals with acute appendicitis who received either surgery or antibiotics. Matching procedures created two initial cohorts, each with 15,774 patients. After excluding those with prior colorectal cancer diagnoses, the analysis focused on 15,616 surgical patients and 15,295 antibiotic-treated patients. In the appendectomy group, 110 cases of colorectal cancer were recorded, compared to 254 cases among those treated with antibiotics only.
The American College of Surgeons showcased this research during the 2026 Clinical Congress in Washington, held from Sept. 26 through 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 distinction remains significant when evaluating the findings. Researchers did not claim that removing the appendix directly reduces cancer risk, nor did the study test appendectomy as a preventative measure for colorectal cancer.
Study explores treatment options following appendicitis
Acute appendicitis results from inflammation of the appendix and typically requires urgent medical intervention. Surgeons often opt for removal through appendectomy, while antibiotics are used for certain uncomplicated cases. The two treatment options formed the basis of this recent investigation. Valentine Nfonsam from Morehouse School of Medicine served as the lead author. He emphasized that antibiotic therapy remains a vital choice for suitable patients, despite the lower incidence of later 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 on the right side of the colon may trigger inflammation of the appendix. Surgical removal provides tissue samples for pathological examination, potentially revealing abnormalities and prompting further testing. Patients treated solely with antibiotics do not undergo such tissue analysis at the time of treatment, creating a notable difference in the potential detection of underlying disease.
The findings do not establish a definitive cancer preventative effect
The appendix contains immune-related tissue and plays a role in the gut’s environment. Its relationship with the gut microbiome, comprising microorganisms living in the digestive tract, has also been studied. However, this analysis did not clarify whether these biological features explain the variation in colorectal cancer diagnoses. The researchers did not find evidence linking inflammation, microbiome alterations, or immune responses directly to the observed differences. As a result, the study suggests an association between treatment type and later cancer diagnosis rates, but does not prove that surgery offers protection against colorectal cancer.
Previous studies have reached different 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. That research found no evidence that appendectomy increased long-term risk of colorectal cancer or precancerous conditions. This new study addresses a more specific question by comparing patients treated surgically for acute appendicitis with those receiving antibiotics alone. Known risk factors for colorectal cancer still include age, family history, and genetic predispositions.