Detection of Missed Colorectal Cancer Remains Low for Most Diverticulitis Patients

Chapel Hill, N.C. –  Acute diverticulitis is a gastrointestinal disease that presents with debilitating pain in the abdomen, anorexia, and malaise. This disease is a common condition that affects older people over 40-years old with a lifetime risk of 3% in men and 5% in women. Colonoscopy is often recommended following an episode of diverticulitis to exclude colorectal cancer (CRC), although researchers say this recommendation was based on limited evidence. Physicians have long been concerned about the potential for a missed CRC in patients presenting with presumed diverticulitis, but research now shows that the risk of CRC is low in most patients with the disease.

“We need to understand the risk of missed cancer to inform whether patients with a history of diverticulitis need a follow up colonoscopy,” said Anne Peery, MD, associate professor of medicine in the Division of Gastroenterology and Hepatology at the UNC School of Medicine.

 A new study published in the Clinical Gastroenterology and Hepatology journal, led by first author Walker Redd, MD, clinical outcomes and epidemiology fellow in the Division of Gastroenterology and Hepatology at the UNC School of Medicine; and corresponding author Anne Peery, MD, associate professor of medicine in the Division of Gastroenterology and Hepatology, now shows that CRC prevalence was 0.33% in colonoscopies for screening and 0.31% in colonoscopies for diverticulitis. Compared to screening, patients with diverticulitis were less likely to have CRC.

 Using data from the Gastrointestinal Quality Improvement Consortium registry, researchers performed a cross-sectional study with patients over 40-years old undergoing outpatient colonoscopy for an indication of diverticulitis follow-up or CRC screening. Researchers identified more than 4-million screening colonoscopies and over 91,000 colonoscopies with a diverticulitis indication. The objective was to determine the prevalence of CRC and advanced colorectal neoplasia (ACN) on colonoscopy in outpatient. ACN includes lesions which might mimic the presentation of diverticulitis. Additionally, CRC symptoms can look similar to diverticulitis and a misdiagnosis can lead to a delay in appropriate treatment. The data was collected between January 2012 and December 2021 at 779 sites across the U.S.

 Researchers found that the overall prevalence of CRC was 0.33% and ACN 6.9% among patients undergoing colonoscopy for the average-risk cancer screening. They also found that the CRC prevalence increased with age for both screening colonoscopies and colonoscopies with a diverticulitis indication. The overall prevalence of CRC for the diverticulitis patients was 0.31% and ACN 5.2%, showing how less likely CRC occurs in this group.

 “Individuals who have had a prior colonoscopy performed more recently will be at lower risk for CRC and those individuals who are undergoing colonoscopy for an indication of diverticulitis may have been more likely to have had a colonoscopy performed more recently than those undergoing colonoscopy for screening which likely explains why the risk of CRC was lower among patients with diverticulitis,” said Redd.

 On the contrary, those with an indication of complicated diverticulitis experienced a different outcome. Results for this group – who had a more severe form of the disease resulting in abscess, obstruction, bleeding or perforation – had a higher prevalence in CRC and ACN. These patients were almost 4-times the risk of CRC when compared to the screening population.

 “The appearance of complicated diverticulitis is more similar to the appearance of a CRC on a CT scan, so it is more likely that a CRC could be mistaken for complicated diverticulitis,” said Redd. “This likely explains why those patients with complicated diverticulitis are more likely to have CRC found on colonoscopy.”

 More than a third of colonoscopies performed for diverticulitis in the researchers’ cohort were for adults ages 40-54 years old. The prevalence of CRC in adults 40-54 years old with diverticulitis was low (0.2-0.3%), but similar to the CRC screening population. Results say that adults ages 40-54 with diverticulitis need thoughtful clinical follow up and may require a follow up colonoscopy.

 “In older patients with diverticulitis, follow up colonoscopy should include consideration of the patient’s overall health status, whether alarm symptoms are present, family history of CRC, findings on any prior colonoscopies, and any notation of concern on imaging,” said Peery.

 The study reports that colonoscopy following an episode of diverticulitis for most patients is unlikely to provide benefit beyond routine colon cancer screening. Researchers believe that these new findings suggest that colonoscopy to detect missed CRC should include diverticulitis patients with a complication, alarming symptoms, and those not current with CRC screening.

 Media Contact: Brittany Phillips, communications specialist UNC Health | UNC School of Medicine