WASHINGTON, D.C. / RankWire.AI / – Individuals who had their appendix removed due to acute appendicitis showed fewer diagnoses of colorectal cancer later on compared to similar patients who were treated solely with antibiotics. Researchers examined 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 who received only antibiotics did. This difference indicates a 58% lower relative risk for patients who had surgery. It is important to note that these findings demonstrate an association, but do not prove 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 intervention or antibiotics. Through matching, they initially formed two groups of 15,774 patients each. After removing patients with prior colorectal cancer diagnoses, the analysis focused on 15,616 surgical patients and 15,295 antibiotic-only patients. Among these, 110 cases of colorectal cancer were found in the appendectomy group, compared to 254 cases in the antibiotic-treated cohort.
This research was presented by the American College of Surgeons during its 2026 Clinical Congress in Washington, held from September 26 to September 29. The study was included in the Scientific Forum program after review for conference presentation, though it has not yet undergone peer review in a medical journal. This status is a key consideration when evaluating the findings. The researchers explicitly stated 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.
Analysis explores different treatment options after appendicitis
Acute appendicitis occurs when the appendix becomes inflamed and typically necessitates urgent medical intervention. Surgeons often opt to remove the appendix surgically, while antibiotics can be an effective treatment for uncomplicated cases. The comparison in this research centered 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 the surgical group.
The investigators also examined clinical factors that could influence the link between appendicitis and colorectal cancer. In some cases, an undetected tumor on the right side of the colon might contribute to inflammation of the appendix. Surgical removal also provides tissue samples for pathological examination, which can reveal abnormalities and lead to further testing. Patients treated solely with antibiotics do not have this tissue examined at the time of treatment, which creates a significant difference in the potential for disease detection.
The results indicate an association but do not establish causation
The appendix contains immune-related tissue and plays a role in the intestinal ecosystem. Researchers have also explored its relationship with the gut microbiome, composed of microorganisms residing in the digestive tract. The current analysis did not clarify whether these biological factors account for the variation in colorectal cancer diagnoses. Additionally, the study did not establish inflammation, microbiome alterations, or immune responses as direct causes of the observed outcome. Therefore, the findings support an association between treatment type and subsequent diagnosis rates, rather than confirming that surgery offers protective benefits against cancer.
Earlier research has arrived at different 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. That investigation found no evidence that appendectomy increased the long-term risk of colorectal cancer or precancerous conditions. The current study narrows its focus to compare patients treated surgically for acute appendicitis with matched patients receiving only antibiotics. Established risk factors for colorectal cancer still include age, family history, and inherited genetic predispositions.