Background: 5-aminosalicylic acids (5-ASAs) have been integral medications in the maintenance and induction of remission in inflammatory bowel diseases (IBD) for the past several decades. These patients have a significantly increased risk for developing colorectal cancer (CRC) when compared to the general population due to the chronic relapsing and remitting inflammatory process that makes neoplasia more likely. It has been shown in recent studies that 5-ASAs have the potential to reduce the risk of CRC in patients with IBD, though the research is not in complete agreement. This review was designed to evaluate the most recent evidence concerning this topic.
Methods: An exhaustive search of available medical literature in MedLINE-Ovid, Web of Science, CINAHL, MD Consult, and Google Scholar databases produced a total of six articles that fit the criteria set before the search. Articles were included if they: 1) assessed CRC prevention using 5-ASA medications in IBD patients, 2) were published during or after 2005, and 3) included odds ratios with 95% confidence intervals or p-values to measure significance.
Results: A total of six retrospective case-control studies were analyzed with a cumulative total of 723 CRC cases and 2113 controls. Four studies resulted in a statistically significant (p < 0.05 or CI < 1) risk reduction in colorectal cancer for IBD patients while the other two studies demonstrated some risk reduction (23-70%) with trends toward significance (p=0.11 and p=0.10 respectively) though they did not reach a p-value less than 0.05.
Conclusion: This systematic review found that the majority of studies do show statistically significant risk reduction of colorectal cancer rates among patients with IBD. Although not all demonstrated statistical significance, all had an odds ratio of less than one, which signifies a certain level of risk reduction. The two studies that did not find statistically significant results both observed the effect of 5-ASA use in control patients for only one year prior to the date of a matched cancer patient’s diagnosis of CRC, leaving into question whether the length of exposure may have skewed the cancer preventing ability of the drug.
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