High frequency of early colorectal cancer in inflammatory bowel disease

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 that surveillance is initiated 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.

A nationwide automated pathology database (PALGA) was consulted to identify patients with IBD-associated colorectal carcinoma in seven university medical centres 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.

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 the entry point, 22% of patients developed cancer before the 8 or 15 year starting points of surveillance, and 28% if surveillance was commenced 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 the surveillance starting points.

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.