Estrogen breakdown affects breast cancer risk

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Estrogen breakdown affects breast cancer risk

 

October 20, 2000

NEW YORK (Reuters Health) - How a woman's body processes the hormone

estrogen may affect her risk of developing breast cancer, new research

suggests.

The good news is that diet and lifestyle affects the way estrogen is

metabolized, so exercising and eating a low-fat diet rich in vegetables may

help reduce the risk of breast cancer by altering estrogen breakdown, the

study's lead author told Reuters Health.

" We have in our hands a potential avenue for prevention, " said Dr. Paola

Muti, of the State University of New York at Buffalo.

Before being removed from the body, estrogen has to go through a " metabolic

filter " in the liver, Muti explained in an interview. This metabolism of

estrogen makes it possible for the hormone to be carried easily through the

blood and eventually excreted in urine, she noted.

But the metabolism, or hydroxylation, of estrogen can take place at two

different locations on the estrogen molecule, according to Muti. When it

takes place at a site called C-16, the process produces " very powerful "

estrogen metabolites that can induce biological activity by linking up with

cell structures called estrogen receptors, she explained. But when it occurs

at the C-2 location, the result is a less active metabolite that can bind to

estrogen receptors but without triggering as much biological activity, Muti

said.

The extra activity of the C-16 metabolites appears to increase the risk of

developing breast cancer, Muti and her colleagues report in the November

issue of the journal Epidemiology. In a study of nearly 11,000 healthy

Italian women who were followed for about 5 years, premenopausal women who

developed breast cancer had a higher percentage of C-16 metabolites in their

urine than women who did not develop cancer.

In postmenopausal women, the way estrogen was metabolized did not appear to

have an effect on cancer risk, according to the report. However, Muti noted

that two other studies have found a connection in older women, so the

results do not necessarily rule out the link in postmenopausal women.

The findings are important, Muti explained, because researchers have not had

as much luck identifying breast cancer risk factors in younger women as they

have in older women. It is too early to say how important a risk factor

estrogen metabolism is, but investigators are on the right track, she said.

Of course, any time a potential target for breast cancer prevention is

identified, one of the first questions to come to mind is whether a drug can

be developed based on the new information. But in Muti's opinion, preventing

cancer through lifestyle changes, though often difficult to make, is

preferable to a pill. She noted that a combination of exercise and a low-fat

diet rich in cruciferous vegetables like cauliflower and broccoli can

favourably change the way estrogen is metabolized.

 

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