WASHINGTON, D.C. / RankWire.AI / – According to recent findings, patients who had their appendix removed due to acute appendicitis experienced fewer subsequent diagnoses of colorectal cancer compared to those treated solely with antibiotics. The study, which looked back at existing data, compared matched groups selected from a comprehensive international health database. Researchers observed colorectal cancer in 0.7% of individuals who underwent an appendectomy. In contrast, the incidence rose to 1.7% among patients who received only antibiotic treatment. This difference equates to a 58% reduction in relative risk within the surgical group.
Utilizing the TriNetX Global Collaborative Network, researchers analyzed data from 168 healthcare organizations. They identified patients diagnosed with acute appendicitis who either received surgery or antibiotics. After matching patients based on relevant characteristics, each group initially comprised 15,774 individuals. The final analysis included 15,616 patients who had an appendectomy and 15,295 who were treated with antibiotics alone, 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.
The findings were presented at the American College of Surgeons Clinical Congress 2026, held in Washington from September 26 to September 29. The research abstract was reviewed and selected by the Scientific Forum program committee. However, no peer review by a medical journal has yet been conducted, which limits the strength of the conclusions. While the study shows an association between the type of treatment and later colorectal cancer diagnoses, it does not prove that removing the appendix prevents the disease.
Comparison of Surgical and Antibiotic Approaches
Acute appendicitis occurs when the appendix becomes inflamed. Located near the junction of the small and large intestines, the appendix has traditionally been removed surgically in many cases, a procedure known as appendectomy. However, antibiotics are increasingly accepted as an alternative treatment 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 significant option despite the new study’s results.
The researchers also explored factors that might influence the development of colorectal cancer after appendicitis treatment. Sometimes, a patient can have an undiagnosed colorectal tumor that causes appendicitis. Tumors on the right side of the colon can obstruct the appendix, leading to inflammation. Surgery provides tissue for pathological examination, which can reveal abnormalities and prompt further testing not typically performed with antibiotic-only treatment.
Study does not confirm cancer prevention effects
The appendix plays a role in immune function through its lymphoid tissue and is linked to the gut microbiome, which includes bacteria and other microorganisms in the digestive system. The recent research, however, did not clarify whether these biological functions explain the variation in colorectal cancer diagnoses. It also did not determine if inflammation or changes in microbes caused the observed association. Consequently, researchers stopped short of claiming that appendectomy acts as a preventive measure against colorectal cancer.
Previous studies have shown mixed results regarding the relationship between appendectomy and colorectal cancer. A 2024 prospective study followed over 224,000 participants across three large cohorts for up to 32 years. It found no evidence that appendectomy increased long-term risks of colorectal cancer or precursors. This new research, however, focuses on comparing patients with appendicitis treated surgically versus those receiving antibiotics alone. Researchers noted that age, family history, and genetics are well-established factors in assessing colorectal cancer risk.