WASHINGTON, D.C. / RankWire.AI / – Patients who had their appendix removed due to acute appendicitis showed a lower rate of subsequent colorectal cancer diagnoses compared to those treated solely with antibiotics. Researchers analyzed matched patient groups within a large international health database. Among those who underwent an appendectomy, 0.7% developed colorectal cancer, whereas 1.7% of patients who received only antibiotics did. This difference indicated a 58% lower relative risk for patients who had surgery. It is important to note that these findings demonstrate an association, not a definitive proof that appendectomy prevents colorectal cancer.
The study utilized data from the TriNetX Global Collaborative Network, which includes records from 168 healthcare organizations. Researchers identified individuals diagnosed with acute appendicitis who were treated either surgically or with antibiotics. After matching patients, two initial groups of 15,774 individuals each were formed. Excluding those with prior colorectal cancer diagnoses, the final analysis included 15,616 surgical patients and 15,295 antibiotic-treated patients. Within these groups, 110 colorectal cancer cases were found in the appendectomy cohort, compared to 254 cases among those treated only with antibiotics.
The American College of Surgeons showcased this research at its 2026 Clinical Congress in Washington from September 26 to September 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 remains critical when evaluating the findings. Researchers emphasized that they did not claim that removing the appendix directly reduces cancer risk, nor did the study test appendectomy as a preventive measure for colorectal cancer.
Analysis explores treatment options following appendicitis
Acute appendicitis involves inflammation of the appendix, often necessitating urgent medical intervention. Surgical removal is a common approach, while antibiotics are sometimes used for uncomplicated cases. The comparison in this new research focused on these two treatment paths. Valentine Nfonsam from Morehouse School of Medicine served as the senior author. He noted that antibiotic therapy remains an essential option for suitable patients, despite the lower incidence 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 cases, an undiagnosed tumor on the right side of the colon might cause inflammation of the appendix. Surgery also allows tissue removal for pathological examination, which can uncover abnormalities and lead to further testing. Patients treated only with antibiotics do not have this tissue examined at the time of treatment, creating a significant difference in how potential disease may be identified.
Findings do not establish a direct protective effect
The appendix contains tissue involved in immune responses and contributes to the gut environment. Studies have also investigated its relationship with the gut microbiome, which includes microorganisms residing in the digestive system. The recent analysis did not clarify whether these biological factors explain the variation in colorectal cancer diagnoses. The researchers also did not determine if inflammation, microbiome alterations, or immune activity caused the observed differences. Consequently, the study indicates an association between treatment type and diagnosis rates, not a confirmed protective effect from surgery.
Prior research has yielded differing 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, finding no evidence that appendectomy increased long-term colorectal cancer or precursor risk. The current study narrows its focus to comparing patients treated for acute appendicitis surgically versus those treated only with antibiotics. Established risk factors such as age, family history, and genetic predispositions remain relevant for colorectal cancer.