WASHINGTON, D.C. / RankWire.AI / – Patients who had their appendix removed due to acute appendicitis showed fewer subsequent diagnoses of colorectal cancer compared to those 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, whereas 1.7% of those treated with antibiotics alone did. This difference indicated a 58% lower relative risk among surgical patients. It is important to note that these results show an association, not proof that appendectomy prevents colorectal cancer.
The study utilized the TriNetX Global Collaborative Network, comprising records from 168 healthcare organizations. Researchers identified individuals diagnosed with acute appendicitis who received either surgical intervention or antibiotics. By matching patients, they established two initial groups of 15,774 individuals each. After excluding those with prior colorectal cancer diagnoses, the final analysis included 15,616 surgical patients and 15,295 antibiotic-treated patients. Among them, 110 cases of colorectal cancer were found in the appendectomy group, compared to 254 cases in the antibiotic-only group.
The research was presented by the American College of Surgeons during its 2026 Clinical Congress in Washington, held from Sept. 26 through Sept. 29. The study was featured in the Scientific Forum program after review for conference presentation but has not undergone peer review in a medical journal. This status remains significant when evaluating the findings. The researchers did not claim that appendectomy directly reduces cancer risk, nor did the study test the procedure as a preventive measure for colorectal cancer.
Investigation explores treatment options following appendicitis
Acute appendicitis occurs when the appendix becomes inflamed, requiring urgent medical care. Common treatments include surgical removal of the appendix or antibiotics for uncomplicated cases. The comparison in this new study focused on these two approaches. Valentine Nfonsam from Morehouse School of Medicine served as the senior author. He emphasized that antibiotic therapy remains a vital treatment choice for suitable patients, despite the lower rate of subsequent colorectal cancer diagnoses observed in those who had surgery.
The researchers also examined clinical factors that could influence the link between appendicitis and colorectal cancer. In some instances, an undiagnosed tumor on the right side of the colon may cause appendix inflammation. Surgical removal allows for tissue examination by a pathologist, potentially revealing abnormalities and prompting further testing. Patients treated with antibiotics alone do not have this tissue analyzed at the time of treatment, which can limit disease detection and influence the observed outcomes.
Findings do not establish a definitive protective effect against cancer
The appendix contains immune-related tissue and plays a role in the intestinal ecosystem. Its relationship with the gut microbiome, which comprises microorganisms in the digestive tract, has also been a subject of study. The current analysis did not clarify whether these biological factors account for the difference in colorectal cancer diagnoses. Researchers did not find inflammation, microbiome alterations, or immune activity as direct causes of the observed results. Therefore, the study indicates an association between treatment type and diagnosis rates rather than a confirmed protective effect of appendectomy against cancer.
Earlier studies have reached varied conclusions regarding appendectomy and long-term colorectal cancer risk. A prospective analysis in 2024 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. The current study focuses on a narrower question by comparing patients who underwent surgery for acute appendicitis with matched patients treated solely with antibiotics. Known risk factors for colorectal cancer still include age, family history, and genetic predispositions.