Foods Interfere With Colon Cancer Drugs
Red Meat and OJ Among Foods That Keep Sulindac, DFMO From Lowering Risk of Colon Polyps
Jan. 25, 2010 (Orlando, Fla.) -- A drug combination that's been found to pack a powerful punch against the risk of colon cancer may only work in people who go light on certain foods, including red meat, corn, and orange juice, a new study suggests.
Two years ago, researchers reported that a combination of the targeted cancer agent DFMO and the arthritis drug sulindac lowered the risk of colon polyps that can lead to colon cancer.
Now, the same research team has found that the drugs' dramatic polyp-lowering effect may be limited to people with a low intake of foods rich in polyamines -- chemicals in food that have been linked to an increased risk of colon cancer.
DFMO and sulindac "clearly had no benefit" in people who consume a lot of polyamines in their diet, says researcher Kavitha Raj, MD, of the University of California, Irvine.
The findings were presented at the 2010 Gastrointestinal Cancers Symposium (GCS), sponsored by the American Society of Clinical Oncology and three other cancer groups.
Colon cancer struck about 160,000 Americans in 2009. The risk of a person getting colon cancer in his or her lifetime is about one in 19, according to the American Cancer Society.
The Role of Polyamines
For the new study, Raj and colleagues went back and reanalyzed data on about 200 people who participated in their original study of DFMO and sulindac. All had at least one colorectal polyp, also known as adenomas, removed in the past year.
Participants were divided into four groups depending on their level of polyamine intake.
First, the researchers analyzed tissue samples that had been taken from the participants before they started the study. They found that compared with those with the lowest intake, people with the highest consumption of polyamines had larger polyps and more advanced polyps with a greater odds of going on to cancer.
Then the researchers looked at the impact of polyamine levels on the study results. In the study, patients were assigned to treatment with either a combination of DFMO and sulindac, or placebo.
In the original study, in which participants were not stratified by polyamine intake, colonoscopy exams after three years showed that people who took DFMO and sulindac were 70% less likely to develop a new polyp, compared with people given a placebo.