ROANOKE TIMES
Copyright (c) 1997, Roanoke Times
DATE: Thursday, February 27, 1997 TAG: 9702270029
SECTION: NATIONAL/INTERNATIONAL PAGE: A-1 EDITION: METRO
DATELINE: BOSTON
SOURCE: Associated Press
The strength of a woman's bones may be the most powerful predictor of her risk of breast cancer.
For the second time in recent months, a study has found that older women with very strong, healthy bones run a sharply higher risk of breast cancer, which kills 44,000 people in the United States annually.
Having strong bones is ordinarily thought to be a good thing, and the bones themselves are almost certainly not the problem. Rather, doctors think healthy bones reflect a high lifetime exposure to estrogen, the female sex hormone also implicated in breast cancer.
``The suspected link is estrogen - not the kind that doctors give you when you enter menopause, but the kind that is naturally occurring in the body during a woman's premenopausal years,'' Dr. Douglas Kiel said.
Kiel, a geriatrics specialist at the Hebrew Rehabilitation Center for the Aged in Boston, is co-author of a study in today's issue of the New England Journal of Medicine. It found that older women with the strongest bones have almost four times the breast cancer risk of women with weak bones.
This could make bone strength the single most powerful predictor of breast cancer risk - even more telling than a family history of the disease, which increases risk two to three times.
Weak bones - a condition called osteoporosis - are extremely common among elderly women. Many already are routinely given a test for bone strength, which costs about $100.
Kiel said he does not yet urge wholesale bone testing to estimate cancer risk. But he said that when the test is already done for other reasons, it can be combined with other known risk factors to help single out women who are at especially high risk.
Knowing their risk is especially great should encourage women to get yearly mammograms, already recommended for all those over 50.
The findings were drawn from the landmark Framingham Heart Study, which has followed the health of residents of a Boston suburb since 1948. In this analysis, doctors reviewed the cases of 1,373 postmenopausal women who got bone density tests between 1967 and 1970.
By 1993, 91 of them had developed breast cancer. The researchers divided the women into four categories of bone strength. Only those in the top category had a significantly elevated risk of breast cancer.
Kiel cautioned that the findings in no way mean that women shouldn't try to keep their bones healthy. While estrogen production powerfully influences bone strength, exercise and calcium in the diet also can help keep bones strong and do not increase cancer risk.
He said the findings offer no evidence for or against giving estrogen supplements after menopause, since the bone density in his study largely resulted from the women's estrogen levels during their reproductive years.
Doctors routinely give estrogen to ease the hot flashes and other symptoms of menopause. Some women stay on the supplements throughout old age as a way of preventing bone loss and heart disease, a far bigger killer than breast cancer.
Nevertheless, Dr. Elizabeth Barrett-Connor of the University of California, San Diego said the study raises fresh doubts about the advisability of this treatment.
``It looks like women with more lifetime estrogen exposure have more breast cancer. You have to ask whether this is also possibly true for estrogen replacement therapy. This paper doesn't tell you that. It raises the possibility,'' Barrett-Connor said.
Estrogen has long been suspected of playing a crucial role in the development of breast cancer. Going through puberty at an especially early age, having few or no children, and late menopause all raise a woman's natural exposure to estrogen, and all of these factors are linked to an increased risk of breast cancer. Receiving estrogen in birth control pills does not appear to affect the risk.
``If your mother had breast cancer, you started periods at an early age, had menopause at a late age, had few or no children, and have great bones, you ought to be getting a mammogram every year,'' Kiel said.
In a November report in the Journal of the American Medical Association, Dr. Jane A. Cauley and others from the University of Pittsburgh reported a similar link between bone density and breast cancer risk in 6,854 older women followed for three years.
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