WASHINGTON, D.C. / RankWire.AI / – According to new research, patients who had their appendix removed due to acute appendicitis showed a significantly lower incidence of subsequent colorectal cancer compared to those treated solely with antibiotics. The retrospective analysis compared matched groups drawn from a large international health database. Researchers discovered colorectal cancer in 0.7% of patients who underwent an appendectomy. In contrast, the rate was 1.7% among patients who received only antibiotics. This difference indicates a 58% lower relative risk in the surgical group.
The study utilized data from the TriNetX Global Collaborative Network, which encompasses information from 168 healthcare organizations. Researchers identified individuals with acute appendicitis who either received surgery or antibiotic therapy. After matching patients based on relevant factors, each group initially included 15,774 individuals. The final analysis involved 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 Sept. 26 through Sept. 29. The research abstract was reviewed and selected by the Scientific Forum program committee. However, no medical journal has yet peer-reviewed the study. This limits the strength of the conclusions that can be drawn. While the research establishes an association between treatment type and subsequent colorectal cancer diagnosis, it does not prove that appendectomy prevents colorectal cancer.
Comparison Between Surgical and Antibiotic Treatments
Acute appendicitis is a condition where the appendix becomes inflamed. The appendix is situated near the junction of the small and large intestines. Traditionally, many cases are treated with surgical removal, known as an appendectomy. Recently, antibiotics have 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 therapy remains an important option despite the findings of this study.
The researchers also explored factors that might influence the development of colorectal cancer following appendicitis treatment. Sometimes, appendicitis occurs in patients who already harbor an undiagnosed colorectal tumor. Tumors on the right side of the colon can obstruct the appendix, leading to inflammation. Surgery provides tissue for pathological examination after the appendix is removed. Such analysis can detect abnormalities and prompt additional diagnostic procedures, which are not typically performed immediately in cases treated solely with antibiotics.
Study Does Not Confirm Cancer Prevention
The appendix plays a role in immune function due to its lymphoid tissue and is linked to the gut microbiome—comprising bacteria and other microorganisms in the digestive system. The recent study did not determine whether these biological functions explain the difference in colorectal cancer diagnoses. It also did not establish whether inflammation or changes in microbial populations caused the observed association. Consequently, researchers stopped short of suggesting that appendectomy serves as a method of cancer prevention.
Previous studies have shown mixed results regarding the relationship between appendectomy and colorectal cancer. A 2024 prospective analysis tracked more than 224,000 participants over up to 32 years across three large cohorts. It found no evidence that having an appendectomy increased the long-term risk of colorectal cancer or precancerous conditions. This new research, however, investigates a different question by comparing patients with appendicitis who were treated surgically to those who received only antibiotics. Researchers noted that age, family history, and genetic predisposition remain key factors in assessing colorectal cancer risk.