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 groups within a large international health database. The data revealed that 0.7% of patients who underwent an appendectomy developed colorectal cancer, while 1.7% of those treated with antibiotics alone did. This difference indicated a 58% lower relative risk among patients who had surgery. It’s important to note that these findings demonstrate an association, not proof that appendectomy prevents colorectal cancer.
The study utilized the TriNetX Global Collaborative Network, which includes records from 168 healthcare organizations. Researchers identified individuals with acute appendicitis who received either surgical intervention or antibiotics. By matching patients, they initially formed two groups of 15,774 each. After excluding those with prior colorectal cancer diagnoses, the final analysis involved 15,616 surgical patients and 15,295 patients treated only with antibiotics. Among these, 110 cases of colorectal cancer were found in the appendectomy group, compared to 254 cases in the antibiotic-only group.
The American College of Surgeons highlighted 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 following review for conference presentation. However, it has not yet undergone peer review in a medical journal. This status is significant when evaluating the results. The researchers did not claim that removing the appendix directly reduces cancer risk. Nor did the study test appendectomy specifically as a preventive measure against colorectal cancer.
Analysis explores different treatment options after appendicitis
Acute appendicitis occurs when the appendix becomes inflamed, often requiring urgent medical attention. Surgeons typically remove the appendix through surgery, but antibiotics can be an effective treatment for select uncomplicated cases. The comparison in this research was based on these two approaches. Valentine Nfonsam of Morehouse School of Medicine served as the senior author. He emphasized that antibiotic therapy remains an important option for suitable patients, despite the lower rate 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 patients, an undiagnosed tumor in the right side of the colon might cause inflammation of the appendix. Surgery also allows for tissue removal and examination by a pathologist. Such analysis can reveal abnormalities and lead to additional testing. Patients treated only with antibiotics do not have tissue examined at the time of treatment, which creates a significant difference in the detection of potential disease.
Findings do not definitively establish a protective effect
The appendix contains immune-related tissue and is part of the intestinal ecosystem. Scientists have also studied its connection to the gut microbiome, which includes microorganisms living in the digestive tract. This analysis did not determine whether these biological features explain the difference in colorectal cancer diagnoses. Researchers also did not establish inflammation, microbiome alterations, or immune responses as causes of the observed association. Therefore, the study suggests a link between treatment type and later diagnosis rates, but does not confirm that surgery offers protection from cancer.
Previous studies have reached varying conclusions regarding appendectomy and long-term colorectal cancer risk. A 2024 prospective study followed over 224,000 participants across three major cohorts for up to 32 years. That research found no evidence that appendectomy increased long-term colorectal cancer or colorectal precursor risk. The current study narrows its focus to compare patients treated for acute appendicitis via surgery with those treated solely with antibiotics. Known risk factors for colorectal cancer include age, family history, and genetic predispositions.