"There is ample epidemiological and experimental data suggesting the a high intake of calcium may decrease the risk of colorectal cancer," Dr. John A. Baron from Dartmouth Medical School in Lebanon, New Hampshire, said during a briefing at the May 2005 meeting of the American Association for Cancer Research.
In 1999, data from the Calcium Polyp Prevention Study involving 930 adults, who were randomly assigned to take an inactive placebo or 1200 milligrams calcium daily for 4 years, showed a 20 percent reduction in the risk of all colorectal cancers with calcium supplementation.
At the meeting, Baron reported data on 822 of the original participants who were followed for at least 5 years after the end of the treatment phase of the study. During that period, there was a 41 percent reduction in the risk of polyps and a 35 percent reduction in risk of all colon cancers. "These were more pronounced reductions than were seen during the treatment phase," Baron said. This reduction in risk did not persist beyond 5 years after the calcium supplements were stopped.
These data, Baron said, indicate that "calcium is effective in reducing the risk of colorectal adenomas and, after the end of the supplementation, there is no rebound in risk at all. In fact there appears to be a delayed, more pronounced suppression of colorectal neoplasia during the 5 years after treatment."
April 2005 Meeting of the American Association for Cancer Research