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Hormone therapy protects against colon cancer
Source: (cancerfacts.com)
Thursday, April 23, 2009
DENVER – April 23, 2009 (cancerfacts.com) – Use of hormone therapy was associated with a significantly lower colorectal cancer risk a large study led by Mayo Clinic scientists has found. The mechanisms for the apparent protective association, however remain unclear.
The study, led by Dr. David Limsui, a fellow in the Department of Gastroenterology at Mayo Clinic's campus in Rochester, Minn. was presented at the American Association of Cancer Research 100th Annual Meeting 2009 held this week in Denver. It was designed to look at possible links between estrogen exposure and coloncancer molecular interactions to determine how these hormones might function as anti-cancer agents. While the study confirmed the protective effect of hormone therapy against colorectal cancer, the researchers did not find the biological basis for the protection.
"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," Limsui said in a prepared statement. "But we still don't know how estrogen compounds work in cancer prevention, which is intriguing."
The study is part of the Iowa Women's Health Study, which enrolled 41,836 women from Iowa, aged 55-69, in 1986. After exclusions, the study group consisted of 37,285 women. In the current analysis, the investigators examined tumor tissue from 553 colorectal cancer patients specifically looking for associations between self-reported hormone use and a specific pattern of molecular interactions resulting from gene mutations. Despite the lower incidence of colorectal cancer among those who used hormones, they detected no association between hormone use and these molecular markers.
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 says.
He adds that other studies have also found that hormone therapy protects postmenopausal women against colon cancer. The largest randomized clinical trial was the 160,000-participant Women's Health Initiative, which concluded in 2004 that combination hormone therapy (estrogen and progestin) reduced a woman's risk of colorectal cancer by about 40 percent, he says.
"But few studies have delved deeper to see how these hormones work at the molecular level," Dr. Limsui says.
SOURCE: adapted from press materials issued by the Mayo Clinic
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