WASHINGTON, D.C. / RankWire.AI / – In Washington, at the American College of Surgeons Clinical Congress 2026, new research revealed that patients who had their appendix removed due to acute appendicitis showed a lower incidence of subsequent colorectal cancer compared to those treated solely with antibiotics. The retrospective analysis utilized a large international health database. Researchers reported colorectal cancer in 0.7% of individuals who underwent an appendectomy. This rate was 1.7% among patients who received only antibiotics. The difference translated into a 58% lower relative risk for the surgery group.
The study employed data from the TriNetX Global Collaborative Network, which compiles information from 168 healthcare organizations. Researchers identified patients diagnosed with acute appendicitis who were treated either with surgery or antibiotics. After matching participants based on relevant characteristics, each group initially comprised 15,774 individuals. Following the exclusion of those with earlier colorectal cancer diagnoses, the final analysis included 15,616 appendectomy patients and 15,295 antibiotic-treated patients. The records indicated 110 colorectal cancer cases following appendectomy and 254 cases after antibiotic-only treatment.
The findings were presented during the Scientific Forum at the American College of Surgeons Clinical Congress 2026, held from September 26 to September 29 in Washington. The research abstract was reviewed and selected by the program committee. However, the study has not yet undergone peer review by a medical journal. This limits the strength of the conclusions, as the research shows an association between treatment type and later colorectal cancer diagnosis but does not prove that appendectomy prevents the disease.
Comparison of Surgical and Antibiotic Approaches
Acute appendicitis involves inflammation of the appendix, which is located near the junction of the small and large intestines. Traditionally, many cases are treated with surgical removal, known as an appendectomy. In recent years, antibiotics have also become an accepted alternative for selected patients. Senior author Valentine Nfonsam, a professor and executive vice chair of surgery at Morehouse School of Medicine, emphasized that antibiotic treatment remains an important option despite the findings of this study.
The researchers also analyzed potential factors influencing colorectal cancer development after appendicitis treatment. They noted that sometimes an undiagnosed colorectal tumor can cause appendicitis, especially if a tumor on the right side of the colon obstructs the appendix, leading to inflammation. Surgery provides tissue for pathological examination, which can reveal abnormalities and prompt further diagnostic testing not typically performed with antibiotic-only treatment.
Study Does Not Confirm Cancer Prevention
The appendix contains lymphoid tissue and plays a role in immune functions within the gut. It has also been linked to the gut microbiome, comprising bacteria and other microorganisms in the digestive system. The recent study did not clarify whether these biological functions explain the differences in colorectal cancer diagnoses or if inflammation or microbial shifts are responsible for the observed association. As a result, researchers stopped short of suggesting that appendectomy acts as a cancer preventive measure.
Previous studies have yielded mixed results regarding the relationship between appendectomy and colorectal cancer. For instance, a 2024 prospective analysis tracked more than 224,000 participants across three large cohorts over a span of up to 32 years. This research found no evidence that having an appendectomy increased long-term risk for colorectal cancer or precursors. The new study, however, focused on comparing patients with appendicitis who underwent surgery versus those treated with antibiotics alone. Researchers highlighted that age, family history, and genetic predisposition remain well-established factors influencing colorectal cancer risk.