Background & Aims:
Inflammatory bowel disease (IBD) can require surgical resection and also lead to colorectal cancer (CRC). We investigated the cumulative incidence of resection surgeries and CRC among patients with ulcerative colitis (UC) or Crohn’s disease (CD).

Methods:
We analyzed data from a cohort of patients who participated in an IBD study (504 with UC and 377 with CD) at 2 academic medical centers in Sydney, Australia from 1977 to 1992 (before the development of biologic therapies). We collected follow-up data on surgeries and development of CRC from hospital and community medical records or via direct contact with patients, over a median time period of 14 y. Cumulative incidences of resection surgeries and CRC were calculated by competing risk survival analysis.

Results:
Among patients with UC, CRC developed in 24, for a cumulative incidence of 1% at 10 y (95% confidence interval [CI], 0−2%), 3% at 20 y (95% CI, 1%−5%), and 7% at 30 y (95% CI, 4%−10%). Their cumulative incidence of colectomy was 15% at 10 y (95% CI, 11%−19%), 26% at 20 y (95% CI, 21%−30%) and 31% at 30 y (95% CI, 25%−36%). Among patients with CD, 5 of 327 with colon disease developed CRC, with a cumulative incidence of CRC of 1% at 10 y (95% CI, 0−2%), 1% at 20 y (95% CI, 0−2%), and 2% at 30 y (95% CI, 0−4%). Among all patients with CD, the cumulative incidence of resection was 32% at 5 y (95% CI, 27%−37%), 43% at 10 y (95% CI, 37%−49%), and 53% at 15 y (95% CI, 46%−58%). Of these 168 subjects, 42% required a 2nd resection within 15 y of the first surgery (95% CI, 33%−50%).

Conclusion:
Patients with UC have a low incidence of CRC over a 30 y period (7% or less); the incidence among patients with CD is even lower. However, almost one third of patients with UC and about 50% of those with CD will require surgery.