WASHINGTON, D.C. / RankWire.AI / – The American College of Surgeons Clinical Congress 2026 showcased new findings from researchers who analyzed data suggesting a link between appendectomy and a significantly lower risk of developing colorectal cancer later in life. The study, based on a large international health database, compared patients treated for acute appendicitis with either surgery or antibiotics. Researchers observed colorectal cancer in 0.7% of those who underwent appendectomy, compared to 1.7% among patients who received antibiotics alone. This difference indicated a 58% lower relative risk in the surgical group.
Utilizing the TriNetX Global Collaborative Network, which aggregates data from 168 healthcare organizations, the team identified individuals with acute appendicitis who were treated either with surgery or antibiotics. After matching patients based on relevant characteristics, each group initially comprised 15,774 individuals. Following the exclusion of those with prior colorectal cancer diagnoses, the final analysis included 15,616 patients who had appendectomy and 15,295 who were treated with antibiotics only. The records revealed 110 cases of colorectal cancer after appendectomy and 254 cases following antibiotic treatment.
Presented at the American College of Surgeons Clinical Congress 2026 in Washington from September 26 to 29, the research abstract was selected by the Scientific Forum program committee for presentation. However, no peer review by a medical journal has yet been conducted, which limits the ability to draw definitive conclusions. While the study shows an association between the type of treatment for appendicitis and later colorectal cancer diagnosis, it does not prove that removing the appendix prevents the development of colorectal cancer.
Comparison of Surgical and Antibiotic Approaches
Acute appendicitis occurs when the appendix becomes inflamed. The appendix, located near the junction of the small and large intestines, has traditionally been removed surgically through an appendectomy. In recent years, antibiotics have also gained acceptance as a treatment option for selected patients. Valentine Nfonsam, senior author and professor as well as executive vice chair of surgery at Morehouse School of Medicine, emphasized that antibiotic therapy remains a crucial choice despite the new findings.
The research team also explored factors that might influence the development of colorectal cancer following appendicitis treatment. Sometimes, an undiagnosed colorectal tumor may cause appendicitis, especially if a tumor on the right side of the colon obstructs the appendix and causes inflammation. Surgery provides tissue for pathological examination, which can reveal abnormalities and prompt further testing that might not be immediately performed with antibiotic-only treatment.
Study Does Not Confirm Cancer Prevention Role
Since the appendix contains lymphoid tissue and plays a role in immune functions within the gut, research has also associated it with the gut microbiome, which includes bacteria and other microorganisms. The current study did not determine whether these biological functions explain the observed differences in colorectal cancer diagnoses, nor whether inflammation or microbial changes are responsible for the association. Therefore, researchers stopped short of claiming that appendectomy can serve as a cancer prevention method.
Previous studies have yielded mixed results regarding the relationship between appendectomy and colorectal cancer. A 2024 prospective analysis followed over 224,000 participants across three large cohorts for up to 32 years, finding no evidence that appendectomy increases long-term risk of colorectal cancer or precursors. The new investigation addresses a different aspect by comparing patients with appendicitis treated surgically to similar patients receiving antibiotics alone. The researchers noted that factors such as age, family history, and genetic predisposition remain key in assessing colorectal cancer risk.