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Hormone replacement therapy and colon cancer

Los Angeles Times

Far fewer women take hormone replacement therapy than did a decade ago, but the drugs are a mixed bag of risks and benefits, as studies occasionally point out. For women who are especially concerned about colon cancer, hormone therapy might be a good idea.

A study has found that using hormone replacement therapy for any length of time cut the risk of distal colon cancer in half. The distal part of the colon is closest to the rectum. The longer women took hormone therapy, the greater the reduced risk. The study involved a comparison of 443 with distal colon cancer and 405 healthy women.

While previous studies, including the Women's Health Initiative, have also linked hormone therapy to a reduced risk of colon cancer, the effects of the drug on the distal colon (where tumors can sometimes act more like rectal cancer) is significant. Moreover, the protective effect appeared to extend to women of all races. The study found that taking oral contraceptives, however, did not reduce the risk of distal colon cancer.
After the results of the Women's Health Initiative appeared in 2002, hormone replacement therapy prescriptions plunged by at least 50%. That study found the drugs can increase the risk of heart attack, stroke and breast cancer in post-menopausal women. Colon cancer rates in women have been on the decline for much longer. But whether the rates of distal colon cancer in women will rise now that hormone therapy is out of favor is a reasonable question, said the authors, from the University of North Carolina, Chapel Hill.

"Much of the reduced incidence of distal large bowel cancer observed in the past two decades may have been partially related to long-term hormone replacement therapy use that is no longer recommended based on the risk-benefit ratio observed in the [Women's Health Initiative,]" they wrote.

The study was released in the American Journal of Gastroenterology.

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