Study links appendix removal to lower colorectal cancer risk
In short
An analysis of more than 30,000 patients found that those who had an inflamed appendix surgically removed were less likely to develop colorectal cancer later than those treated with antibiotics alone. Colorectal cancer was diagnosed in 0.7% of the appendectomy group versus 1.7% of the antibiotics group, a 58% lower relative risk after adjusting for individual risk factors. The study leader said the results do not mean all appendicitis patients should have surgery to prevent cancer, and that antibiotics remain an important option.
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Patients whose inflamed appendix was surgically removed were significantly less likely to be diagnosed with colorectal cancer later than patients treated with antibiotics alone, according to an analysis of more than 30,000 cases presented at the American College of Surgeons Clinical Congress in Washington. [ 1 , 2 ]
The researchers reviewed records for 15,774 patients diagnosed with acute appendicitis who underwent an appendectomy and another 15,295 treated with antibiotics alone. Colorectal cancer was subsequently diagnosed in 0.7% of the appendectomy group and 1.7% of the antibiotics group. After accounting for individual risk factors, appendectomy was associated with a 58% lower relative risk of a later colorectal cancer diagnosis. [ 1 , 2 ]
Study leader Dr. Valentine Nfonsam of Morehouse School of Medicine in Atlanta said management of acute appendicitis “has changed significantly over the last decade, and antibiotic therapy is now an accepted option.” He said the appendix was once thought to be useless, but that emerging research suggests it may play a role in the intestinal immune system and in the gut microbiome. [ 1 ]
Nfonsam cautioned against reading the results as a general case for surgery: “These results should not be interpreted to mean that everyone with appendicitis needs an appendectomy to prevent cancer,” he said, adding that “antibiotic management remains an important option.” He said that when doctors discuss non-operative management, they should think beyond the immediate episode of appendicitis and consider potential long-term cancer risk and appropriate monitoring. [ 1 , 2 ]
Nfonsam said it is biologically plausible that persistent inflammation or changes in the gut microbiome contribute to the development of cancer, but that the study was not designed to answer that question. WAM reported that further research is needed to examine links between appendicitis, microbiome changes and cancer risk. [ 1 , 2 ]
Why it matters
The finding adds a long-term consideration to a treatment choice that has shifted over the past decade, as antibiotics have become an accepted alternative to surgery for acute appendicitis. The study leader said doctors discussing non-operative management should look beyond the immediate episode. The research was presented at a medical conference, and the documents say further work is needed before any link between appendicitis, the gut microbiome and cancer risk is established.
Key facts
- The analysis covered more than 30,000 cases of acute appendicitis. [ 1 , 2 ]
- Researchers reviewed records for 15,774 patients who had an appendectomy and 15,295 treated with antibiotics alone. [ 1 , 2 ]
- Colorectal cancer was later diagnosed in 0.7% of the appendectomy group and 1.7% of the antibiotics group. [ 1 , 2 ]
- After accounting for individual risk factors, appendectomy was associated with a 58% lower relative risk of a later colorectal cancer diagnosis. [ 1 , 2 ]
- The findings were presented at the American College of Surgeons Clinical Congress in Washington. [ 1 , 2 ]
- Study leader Dr. Valentine Nfonsam of Morehouse School of Medicine said the appendix may play a role in the intestinal immune system and the gut microbiome. [ 1 , 2 ]
- Nfonsam said the results should not be read as a reason for everyone with appendicitis to have surgery to prevent cancer, and that antibiotics remain an important option. [ 1 , 2 ]
- The study was not designed to determine whether persistent inflammation or microbiome changes contribute to cancer development, Nfonsam said. [ 1 ]
Confirmed by several sources
- The analysis covered more than 30,000 patients, with colorectal cancer diagnosed in 0.7% of the appendectomy group and 1.7% of the antibiotics group. [ 1 , 2 ]
- Appendectomy was associated with a 58% lower relative risk of a subsequent colorectal cancer diagnosis after adjusting for individual risk factors. [ 1 , 2 ]
- The findings were presented at an American College of Surgeons conference in Washington. [ 1 , 2 ]
- The study leader said antibiotics remain an important treatment option and that the findings do not mean all appendicitis patients should have surgery to prevent cancer. [ 1 , 2 ]
Still unclear
- Whether persistent inflammation or changes in the gut microbiome contribute to the development of cancer. The study was not designed to answer that question, the study leader said; WAM reported that further research is needed.
- Whether the research has been peer-reviewed or published in a journal. Both documents describe the results only as presented at a medical conference.
- Details of the conference presentation itself, such as its date and time. The documents give no time for the presentation, only the dates on which the two reports were published.