WASHINGTON, D.C. / RankWire.AI / – In a study conducted using data from an international health database, patients in different countries who had their appendix removed due to acute appendicitis showed fewer diagnoses of colorectal cancer compared to those treated solely with antibiotics. Researchers matched patient groups from various healthcare organizations. The analysis revealed that 0.7% of patients who underwent an appendectomy developed colorectal cancer, whereas 1.7% of those who only received antibiotics did. This translated to a 58% lower relative risk for the surgical group. The results suggest an association, but do not establish that appendectomy prevents colorectal cancer.
The investigation utilized the TriNetX Global Collaborative Network, which encompasses records from 168 healthcare providers. Researchers identified individuals diagnosed with acute appendicitis who either received surgery or antibiotics. After matching, two initial cohorts 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 antibiotic-only patients. The study found 110 colorectal cancer cases among those who had an appendectomy and 254 among patients treated with antibiotics only.
The American College of Surgeons showcased this research during its 2026 Clinical Congress in Washington, held from Sept. 26 to Sept. 29. The study 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 important 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 method of colorectal cancer prevention.
Study explores treatment options following appendicitis
Acute appendicitis occurs when the appendix becomes inflamed, often requiring urgent medical intervention. Surgical removal is a common approach, although antibiotics are sometimes used for uncomplicated cases. The comparison in this new research centered on these two treatment strategies. Valentine Nfonsam of Morehouse School of Medicine served as the lead author. He emphasized that antibiotic therapy remains a key treatment choice for suitable patients, despite the lower rate of subsequent colorectal cancer diagnoses observed among those who had surgery.
The study also considered clinical factors that could affect the link between appendicitis and colorectal cancer. In certain cases, an undiagnosed tumor on the right side of the colon may contribute to appendix inflammation. Surgical intervention provides tissue samples for pathological examination, which can uncover abnormalities and lead to further testing. Patients treated solely with antibiotics do not have this tissue examined at the time of treatment, creating a significant difference in the potential detection of underlying disease.
Findings do not definitively prove cancer prevention
The appendix contains immune-related tissue and plays a role in the gut environment. Researchers have also examined its connection to the gut microbiome, which comprises microorganisms in the digestive system. The current analysis did not clarify whether these biological factors account for the difference in colorectal cancer diagnoses. It also did not establish inflammation, changes in microbiome composition, or immune activity as causes of the observed association. Thus, the study indicates a correlation between treatment method and later diagnosis rates without confirming a protective effect of appendectomy against cancer.
Previous studies have reached varying 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 increases long-term colorectal cancer risk or precursor risk. The current study focuses on a narrower question by comparing patients treated for acute appendicitis with surgery against matched patients treated only with antibiotics. Key colorectal cancer risk factors such as age, family history, and genetic predispositions remain relevant.