Higher blood levels of selenium are associated with lower rates of colorectal cancer recurrence, according to a new report.

Studies of the effects of selenium on colorectal cancer have been about evenly divided between those that show a protective effect or no effect. As Dr. Elizabeth T. Jacobs and colleagues explain in the Journal of the National Cancer Institute, these studies were limited by the small number of participants.

Jacobs, at the University of Arizona in Tucson, and her colleagues pooled data from three completed trials that were originally designed to test the effects of nutritional interventions on cancer recurrence in patients who had undergone colon cancer surgery. None of the interventions included selenium supplementation.

After adjustment for age, gender and smoking, each of the trials showed a lower risk of recurrence in subjects with the highest blood selenium level versus those with the lowest - although only one gave a result that was significant from statistical standpoint.

Analysis of the pooled data showed a progressive decrease in the likelihood of colon cancer recurring with increasing levels of selenium, with a 44-percent reduction for the highest compared with the lowest level.

So it is possible that selenium supplementation could protect against colon cancer, the authors say, although they note that it is still not known what form of selenium and what amount would be protective.

In an accompanying editorial, Dr. Scott M. Lippman, at the University of Texas M. D. Anderson Cancer Center in Houston, and colleagues suggest that the answers to these questions may be revealed by the Selenium and Vitamin E Cancer Prevention Trial (SELECT), which has already enrolled more than 35,000 men.

SOURCE: Journal of the National Cancer Institute, November 17, 2004.