WASHINGTON, D.C. / RankWire.AI / – Individuals who had their appendix removed due to acute appendicitis showed a lower incidence of subsequent colorectal cancer compared to those treated solely with antibiotics, new research indicates. The retrospective analysis examined matched groups from a comprehensive global health database. Researchers reported colorectal cancer in 0.7% of patients who underwent an appendectomy, whereas the rate was 1.7% among those who received only antibiotics. This difference represented a 58% lower relative risk associated with the surgical procedure.
The study utilized data from the TriNetX Global Collaborative Network, encompassing information from 168 healthcare organizations. Researchers identified patients diagnosed with acute appendicitis who either underwent surgery or received antibiotic therapy. After matching patients based on relevant characteristics, each group initially included 15,774 individuals. The final analysis comprised 15,616 patients who had an appendectomy and 15,295 who were treated with antibiotics after excluding those with prior colorectal cancer diagnoses. The records revealed 110 cases of colorectal cancer following appendectomy, compared to 254 cases in the antibiotic-only group.
These findings were presented at the American College of Surgeons Clinical Congress 2026 in Washington from Sept. 26 through Sept. 29. The research abstract was reviewed and selected by the Scientific Forum program committee. However, the study has not yet undergone peer review by a medical journal, which limits the strength of the conclusions. While the research shows an association between the type of treatment and later colorectal cancer diagnosis, it does not prove that removing the appendix prevents the development of colorectal cancer.
Comparison Between Surgical and Antibiotic Treatments
Acute appendicitis occurs when the appendix becomes inflamed, positioned near the junction of the small and large intestines. Historically, many cases are managed through surgical removal, known as an appendectomy. Recently, antibiotics have also become a recognized alternative for selected patients. Senior author Valentine Nfonsam, a professor and executive vice chair of surgery at Morehouse School of Medicine, emphasized that antibiotic therapy remains a valuable option despite the study’s findings.
The researchers also explored factors that could influence the appearance of colorectal cancer after treatment for appendicitis. Sometimes, a patient may have an undiagnosed colorectal tumor that causes appendicitis; for example, a tumor on the right side of the colon can block the appendix and lead to inflammation. Surgery provides tissue samples for pathological examination, which can detect abnormalities and prompt additional diagnostic testing that is less likely to occur immediately with antibiotic-only treatment.
The Study Does Not Confirm Cancer Prevention
The appendix is rich in lymphoid tissue and plays a role in immune function within the intestinal system. It has also been linked to the gut microbiome, which includes bacteria and other microorganisms in the digestive tract. The current study did not clarify whether these biological functions explain the difference in colorectal cancer diagnoses. It also did not establish whether inflammation or microbial shifts caused the observed association. Therefore, researchers refrained from suggesting that appendectomy acts as a method of cancer prevention.
Previous studies have yielded mixed results regarding the link between appendectomy and colorectal cancer. For instance, a 2024 prospective study followed over 224,000 participants across three large cohorts for up to 32 years, finding no evidence that an appendectomy increases the long-term risk of colorectal cancer or precursors. This new research addresses a different question by comparing patients with appendicitis who underwent surgery to those receiving antibiotics alone. Researchers noted that age, family history, and genetic predispositions remain key factors when evaluating colorectal cancer risk.