WASHINGTON, D.C. / RankWire.AI / – Patients who had their appendix removed due to acute appendicitis showed fewer subsequent diagnoses of colorectal cancer compared to those treated solely with antibiotics, according to recent research. This retrospective study analyzed matched groups drawn from a large international health database. Researchers reported colorectal cancer in 0.7% of patients who underwent an appendectomy. In contrast, the rate was 1.7% among those who received only antibiotics. This difference translated into a 58% lower relative risk for the surgery group.
The study utilized data from the TriNetX Global Collaborative Network, which includes information from 168 healthcare organizations. Researchers identified patients with acute appendicitis who either had surgery or received antibiotics. After matching patients by relevant factors, each group consisted of 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 showed 110 cases of colorectal cancer following appendectomy and 254 cases after antibiotic-only treatment.
The findings were presented at the American College of Surgeons Clinical Congress 2026, held in Washington from Sept. 26 to 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. The study shows an association between treatment type and later colorectal cancer diagnosis but does not prove that removing the appendix prevents the disease.
Comparison of Surgical and Antibiotic Treatments
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. Recently, antibiotics have become an accepted alternative for select patients. Senior author Valentine Nfonsam, a professor and executive vice chair of surgery at Morehouse School of Medicine, emphasized that antibiotic treatment remains a vital option despite these findings.
The researchers also looked into factors that might influence colorectal cancer development after appendicitis treatment. Sometimes, an undiagnosed colorectal tumor can cause appendicitis. A tumor on the right side of the colon can block the appendix and cause inflammation. Surgery provides tissue for pathological examination after removal. This can reveal abnormalities and prompt additional diagnostic tests, which are less likely to happen with antibiotic treatment alone.
Results Do Not Confirm Cancer Prevention
The appendix contains lymphoid tissue and plays a role in immune function within the gut. It is also linked to the gut microbiome, which includes bacteria and other microorganisms. The recent study did not clarify whether these biological functions explain the differences in colorectal cancer diagnoses. It also did not determine if inflammation or microbial changes caused the association. As a result, researchers stopped short of suggesting that appendectomy prevents colorectal cancer.
Previous research has shown mixed results regarding the link 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 colorectal cancer risk or precancerous conditions. This new study addresses a different question by comparing patients with appendicitis who had surgery to those treated with antibiotics alone. Researchers note that age, family history, and genetics remain important factors in assessing colorectal cancer risk.