5-Aminosalicylic acid therapy and the risk of colorectal cancer among patients with inflammatory bowel disease.

BACKGROUND

Patients with inflammatory bowel disease (IBD) affecting the colon are at increased risk of developing colorectal cancer (CRC). Published data are conflicting about whether 5-aminosalicylic acid (5-ASA) has chemopreventive properties against IBD-related carcinogenesis. The objective of this observational study was to determine if an association between 5-ASA therapy and CRC risk exists in IBD patients.

METHODS

Adult patients with a new CRC diagnosis (n = 18,440) were identified from 2 large administrative claims databases. For each case, 20 control patients with no record of CRC diagnosis or bowel surgery (n = 368,800) were identified.

RESULTS

An IBD diagnosis was associated with a 6- to 7-fold increased risk of CRC (ulcerative colitis, crude odds ratio [OR] = 6.72, 95% CI, 5.79-7.81; Crohn's disease, crude OR = 6.60, 95% CI, 5.56-7.82). Among patients with IBD (364 CRC cases, 1172 controls), exposure to 5-ASA therapy of any dose or duration during the 12 months before CRC diagnosis was not associated with a reduced risk of CRC (OR = 0.97; 95% CI, 0.77-1.23). However, there was a trend toward a decreased risk of CRC with increasing number of mesalamine prescriptions in the previous year, though statistical significance was not achieved (trend P = 0.08).

CONCLUSIONS

Treating IBD patients with 5-ASA medications was not found to have a protective effect against colitis-related CRC when assessed over a short period of exposure.