Association Between Inflammatory Bowel Disease and Colorectal Cancer Stage of Disease and Survival.

BACKGROUND: Inflammatory bowel disease (IBD) is associated with an increased risk of colorectal cancer (CRC). However, there are few data comparing outcomes between IBD and non-IBD-associated CRC. METHODS: Retrospective cohort study of patients with CRC identified from the Veteran Affairs (VA) Central Cancer Registry from 1998 to 2012 linked to national VA administrative claims to identify patients with IBD using a previously validated algorithm. The association between IBD status and stage of disease and overall risk of death were evaluated using multivariable logistic and Cox regression, respectively. RESULTS: Among 34,570 CRC patients, 217 had IBD. IBD patients were significantly younger for both colon and rectal cancer. IBD patients who developed rectal cancer were significantly more likely to present with locally advanced or metastatic disease (P = 0.007), but there was no difference in stage among patients with colon cancer. This difference persisted after multivariable adjustment (overall-odds ratio [OR] 1.40, 95% confidence interval [1.03-1.90]; colon-OR 1.22 [0.84-1.78]; rectum-OR 2.04 [1.22-3.40]). Total colectomy was more commonly performed among IBD patients. Overall, IBD was associated with a 52% increased risk of death (hazard ratio 1.52 [1.21-1.91]). CONCLUSIONS: Although IBD is associated with more advanced stage at diagnosis for rectal cancer, it is associated with a worse survival primarily in patients with colon cancer. Further work is needed to better understand the reason for these observed differences between IBD and non-IBD patients and to better delineate the impact of endoscopic surveillance on CRC care and outcomes in IBD patients.