Background & Aim: To detect precancerous dysplasia or asymptomatic cancer, patients suffering from inflammatory bowel disease often undergo colonoscopic surveillance based on American or British guidelines. It is recommended to initiate surveillance after 8-10 years of extensive colitis, or after 15-20 years for left-sided disease. These starting points, however, are not based on solid scientific evidence. Our aim was to assess the time-interval between onset of inflammatory bowel disease (IBD) and colorectal carcinoma (CRC), and subsequently evaluate how many patients developed cancer before their surveillance was recommended to commence.
Methods: A nationwide automated pathology database was consulted to identify patients with IBD-associated colorectal carcinoma in 7 university medical centers in the Netherlands between January 1990 and June 2006. Data were collected retrospectively from patient charts. Time-intervals between onset of disease and cancer diagnosis were calculated in months.
Results: 149 patients were identified with confirmed diagnoses of IBD and CRC (ulcerative colitis n=89 / Crohn's disease n=59 / indeterminate colitis n=1). Taking date of diagnosis as entry-point, 22% of patients developed cancer before the 8 or 15 year starting points of surveillance, and 28% if surveillance would commence 10 or 20 years after diagnosis for extensive or left-sided disease respectively. Using onset of symptoms to calculate the time-interval, 17%-22% of patients would present with cancer prior to surveillance starting points.
Conclusions: These results show that the diagnosis of colorectal cancer is delayed or missed in a substantial number of patients (17-28%) when conducting surveillance strictly according to formal guidelines.