Colorectal cancer incidence following acute diverticulitis

Introduction: Recent meta‐analysis reported the incidence of colorectal cancer is 7.9% following complicated diverticulitis and 1.3% following uncomplicated diverticulitis. Current ACPGBI guidelines advise colonic investigation following an acute episode of diverticulitis. We aimed to assess the incidence of colorectal cancer following episodes of CT‐verified diverticulitis. Method: This was a retrospective cohort study of patients with CT‐proven acute diverticulitis from January 2010 to March 2013. All CT scans in the time period were searched for diverticular terms. Data collected included demographics and diverticulitis classification. Data was cross‐checked with the South‐east Scotland cancer dataset (SCAN) with a minimum of 5 years follow‐up. Results: There were 655 CT‐proven diverticulitis cases in the study period (578 patients, female: 331, median age 62): 265 (45.8%) patients had complicated diverticulitis, 313 (54.2%) uncomplicated diverticulitis. There was no significant difference in age or gender between the complicated and uncomplicated diverticulitis groups (P > 0.05). The overall incidence of colorectal cancer was 1.0% (6 patients). However, there was only one patient (0.17%) diagnosed with cancer in the diverticular segment within a year (8 months). Three patients developed cancers distant from the diverticulitis site. Two patients developed cancer close to the original diverticulitis site at 42 and 91 months. Therefore, at most permissive calculation, 3 patients had cancer diagnosed at diverticulitis segment (overall incidence rate 0.52%, 0.75% (2/265) in complicated group, 0.32% (1/313) in uncomplicated group. Conclusions: The incidence of colorectal cancer following diverticulitis may be lower than previously reported. Hence, guidelines regarding post‐diverticulitis colonic investigation may be adapted locally.