Background: The impact of inflammatory bowel disease (IBD) on colorectal cancer (CRC) prognosis, taking into account other comorbidities, is not clear. We studied the overall mortality in CRC patients with a history of ulcerative colitis (UC) or Crohn's disease (CD) compared with non-IBD-CRC patients.
Methods: Data on all CRC and IBD patients diagnosed with CRC between 1977 and 2009 were retrieved from Danish medical registries. One-year and 5-year overall mortality were evaluated with the Kaplan–Meier method and with Cox regression, adjusting for year of CRC diagnosis, sex, Duke's stage, age at CRC diagnosis, and Charlson Comorbidity Index score.
Results: We identified 653 CRC patients diagnosed with UC, 238 patients with CD, and 107,024 CRC patients without IBD. The patients with IBD were younger at diagnosis than patients without IBD. The Duke's stage distribution was similar for UC-CRC patients and non-IBD-CRC patients. The CD-CRC patients had a lower frequency of Duke's A and B stage tumors (36% versus 42%), a higher frequency of Duke's C stage tumors (31% versus 27%) and Duke's D-stage tumors (23% versus 21%), and a similar frequency of unknown stage tumors (10%) compared with non-IBD-CRC patients. After 5-years of follow-up, 59% of the UC and the non-UC-CRC patients had died compared with 62% of the patients with CD and 56% of the non-CD-CRC patients. The 5-year adjusted mortality rate ratios for patients with UC or CD were 1.14 (95% confidence interval, 1.03–1.27) and 1.26 (95% confidence interval, 1.07–1.49), respectively, compared with patients without IBD.
Conclusion: A history of IBD in patients with CRC may be associated with increased mortality.