Hormone replacement therapy may reduce the risk
of colorectal cancer in women, according to new results of a
meta-analysis presented at the North American Menopause Society meeting.
From the first quantitative review of 18 epidemiologic studies done
in the United States and Europe of the effects of hormone replacement
therapy on colorectal cancer rates in postmenopausal women, Harvard
University researcher Meir Stampfer, md, drph, found that women
currently taking estrogen had up to a 34% reduction in colorectal
cancer rates compared with women who had never used hormones.
Overall, there was a 20% reduction in the rate of colon cancer and a
15% reduction in the rate of rectal cancer among women who had taken
estrogen at some point in their lives. Our analysis strongly
suggests estrogen replacement therapy can help reduce the risk of
colorectal cancer, said Stampfer.
This research finding, although provocative, does not eliminate
the need for colorectal cancer screening, which currently is the only
proven way to prevent colorectal cancer, said Randall W Burt,
md, professor of medicine, University of Utah; program head, Huntsman
Cancer Institute; and a member of the AGA governing board.
Colorectal cancer screening for postmenopausal women should be
taken as seriously as mammograms and Pap smears.
Although researchers are not certain how estrogen affects the colon,
it is possible that it alters the production of bile acids that aid
digestion in the colon and seem to be important for colorectal
cancer. In addition, estrogen interacts with estrogen-specific
receptors that line the colon and could suppress the growth of
Both Drs. Burt and Stampfer agree that further studies are needed to
determine why estrogen may protect postmenopausal women against
colorectal cancer and to shed light on how physicians might prevent
the disease in the future.