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 individuals treated solely with antibiotics. Researchers analyzed matched patient cohorts within a comprehensive international health database. The data revealed that colorectal cancer was diagnosed in 0.7% of patients who underwent an appendectomy, versus 1.7% among those who only received antibiotics. This difference indicates a 58% reduction in relative risk for those who had surgery. It is important to note that these findings suggest an association, not a direct causative effect of appendectomy in preventing colorectal cancer.
The investigation utilized the TriNetX Global Collaborative Network, which encompasses records from 168 healthcare organizations. Researchers identified individuals with acute appendicitis who received either surgical removal or antibiotic treatment. After matching patients, they formed two groups of 15,774 each. Excluding those with prior colorectal cancer diagnoses, the final analysis included 15,616 surgical patients and 15,295 antibiotic-only patients. The study documented 110 cases of colorectal cancer in the appendectomy group, compared to 254 cases among the antibiotic-treated cohort.
The research was highlighted at the American College of Surgeons’ 2026 Clinical Congress in Washington, held from Sept. 26 to Sept. 29. The findings were presented during the Scientific Forum after review for conference presentation, though they have not undergone peer review in a medical journal. This status is significant when interpreting the results. The researchers emphasized that they did not conclude that removing the appendix directly reduces cancer risk, nor was the procedure tested specifically as a preventative measure for colorectal cancer.
Analysis explores treatment options following appendicitis
Acute appendicitis occurs when the appendix becomes inflamed, often necessitating urgent medical intervention. Physicians typically perform surgical removal, although antibiotics can be an effective treatment for uncomplicated cases. The study compared these two approaches to evaluate their potential long-term effects. Valentine Nfonsam of Morehouse School of Medicine served as the senior author, noting that antibiotic therapy remains a vital option for suitable patients despite the lower colorectal cancer rates observed in the surgical group.
The study also considered clinical factors that could influence the connection between appendicitis and colorectal cancer. In some instances, an undetected tumor in the right colon may cause inflammation of the appendix. Surgery allows for tissue removal, which can then be examined by a pathologist. Such examination might identify abnormalities, prompting further diagnostic tests. Patients treated solely with antibiotics do not undergo immediate tissue analysis, creating a significant difference in the potential to detect underlying disease at the time of treatment.
The findings do not definitively prove cancer prevention
The appendix contains immune-related tissue and plays a role within the gut environment. Scientists have also investigated its relationship with the gut microbiome, which includes microorganisms inhabiting the digestive tract. The current analysis did not clarify whether these biological factors account for the difference in colorectal cancer diagnoses. Moreover, the study did not establish inflammation, microbiome alterations, or immune responses as causes of the observed association. Consequently, the research supports a correlation between treatment type and subsequent diagnosis rates, rather than confirming that surgery offers protective benefits against cancer.
Previous studies have produced varying conclusions regarding appendectomy and long-term colorectal cancer risk. For example, a 2024 prospective study tracked over 224,000 individuals across three major cohorts for up to 32 years, finding no evidence that appendectomy increases long-term colorectal cancer risk or precancerous conditions. The current research narrows its focus by comparing patients treated surgically for acute appendicitis with matched individuals who received only antibiotics. Known risk factors for colorectal cancer still include age, family history, and genetic predisposition.