PHILADELPHIA — Treatment with either folic acid or mesalamine was linked to about a 90% reduction in the incidence of colorectal cancer in a case-control study including 48 patients with inflammatory bowel disease.
Both agents “appear to be very promising cancer chemopreventive agents,” but the findings need to be confirmed in additional inflammatory bowel disease (IBD) patients, especially because the study involved such a modest number of patients, Dr. Jeffrey Tang said at the annual meeting of the American College of Gastroenterology.
The analysis showed that patients who took a cumulative dose of at least 4,500 g of mesalamine had a statistically significant, 91% drop in their incidence of colorectal cancer (CRC), said Dr. Tang, a gastroenterologist at Henry Ford Hospital in Detroit. The usual mesalamine dose used by IBD patients at Henry Ford was 1.6 g/day.
Patients who took at least 1 mg of folic acid daily also had about a 90% cut in their CRC incidence during follow-up, compared with the controls. Two additional analyses showed that the effects of mesalamine and folic acid on CRC prevention were completely independent of each other.
“The strength of the associations [in this study] is big and very important,” commented Dr. Carol A. Burke, director of the Center for Colon Polyp and Cancer Prevention at the Cleveland Clinic.
The apparent efficacy of folic acid in patients with IBD in Dr. Tang's study contrasts with a report published in June which found no protective effect from folic acid when it was given to men and women who did not have IBD (JAMA 2007;297:2351–9), she said in an interview.
Both drugs are safe, and the new findings hold promise for using these agents to reduce the risk of CRC in patients with IBD, Dr. Burke said.
Dr. Tang and his associates reviewed the records of 1,784 patients with IBD who were seen at Henry Ford Hospital from 1970 to 2005. During an average follow-up of 8 years, 30 of the patients developed CRC; 25 had ulcerative colitis, and 5 had Crohn's disease.
The researchers then attempted to match each of the incident cases with up to two control patients with IBD who did not develop CRC during an average follow-up of 12 years. A total of 30 control patients were identified to match with 18 of the incident cases. No matches were found for the remaining 12 IBD patients who developed cancer during follow-up, and they were dropped from the analysis.
The cases and controls were similar on several parameters, including gender, race, smoking status, family history, and age when IBD first appeared. The cases included 15 patients with ulcerative colitis and 3 patients with Crohn's disease.