In a large study, a national team of researchers led by Mayo Clinic scientists observed that self-reported use of hormone therapy was associated with a significantly lower colorectal cancer risk.
However, the mechanisms for the apparent protective association are still unclear.
The study, being presented at the AACR 100th Annual Meeting 2009, was designed to look at possible links between estrogen exposure and colon cancer molecular subtypes, to determine how these hormones might function as anti-cancer agents.
"In our large, prospective study, use of hormone therapy seemed to be beneficial with respect to reducing colorectal cancer risk - women who did use these drugs had a 28 percent lower incidence rate than women who did not use these drugs," says the study's lead author, David Limsui, M.D., a fellow in the Department of Gastroenterology at Mayo Clinic's campus in Rochester, Minn. "But we still don't know how estrogen compounds work in cancer prevention, which is intriguing."
Women who reported using other hormone preparations, such as oral contraceptives, did not appear to derive any colorectal cancer prevention benefits. "Based on our findings, we need to continue exploring the cancer pathways that might be affected by these hormones," Dr. Limsui says.