Colorectal Cancer News:

Study: People With High Levels of Selenium Have Less Risk of Colorectal Cancer

High levels of selenium in the blood may reduce the risk of colorectal cancer, according to a study reported in the November 17 issue of the Journal of the National Cancer Institute.

Selenium is a trace mineral found in meats, grains, seafood and some nuts.

"Your risk of colorectal cancer can vary by the amount of selenium you consume," said lead researcher Elizabeth Jacobs, from the Arizona Cancer Center. "People with higher blood selenium levels tended to have a decreased risk of a recurrence of colon cancer."

Jacobs and her colleagues collected data from three randomized trials of colon cancer patients. Looking at the data from these trials, they were able to determine the effect of selenium in the development of new cancerous colon polyps in patients.

The researchers found that those with the highest selenium levels had a 34 percent lower risk of developing a new colon cancer, compared with those who had the lowest selenium levels.

Whether increasing your selenium intake will actually be beneficial is not clear, according to Jacobs. "It will benefit those whose intake of selenium is low," she said. "However, it may not benefit those who already have adequate selenium levels."

The risks of having too much selenium are not known but are being studied, Jacobs said. In addition, studies are under way to determine the optimum selenium levels needed to prevent colon cancer. She noted that ongoing studies are underway to see if selenium can help treat patients with prostate cancer.

Dr. Scott M. Lippman, chairman of the department of clinical cancer prevention at the University of Texas M.D. Anderson Cancer Center, cautioned that the study is not definitive since it is not from a large randomized control trial of selenium.

Lippman, who co-wrote an accompanying journal editorial, said biological reasons exist that may make selenium effective in preventing colon cancer. One of these mechanisms is selenium's role in turning on genes that prevent cancer. Another is the mineral's effect in altering the metabolism of polyunsaturated fatty acids found in red meats, which are involved in the development of colorectal cancer, he said.

However, Lippman cautioned that the results of this study do not mean that people should start taking selenium supplements in the hope of preventing cancers.

Source:Medical Week staff, November 20, 2004