A team of researchers led by Mayo Clinic scientists has found that hormone therapy use is linked to a significantly lower colorectal cancer risk.
However, the mechanisms for the apparent protective association are still unclear.
The study 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," he added.
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," Limsui said.
In the study, the researchers examined tumour tissue from 553 colorectal cancer patients, specifically looking for associations between self-reported hormone use and a specific DNA methylation pattern, called the CpG island methylator phenotype, or BRAF gene mutations.
No associations were detected between hormone use and these molecular markers.
The study is being presented at the AACR 100th Annual Meeting 2009.