Women With Breast Cancer More Prone to Fractures, Says New Study

Contrary to a widely held belief, high bone density is no guarantee against osteoporosis in breast cancer patients, a U.S.-Israeli study shows.

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The conventional wisdom is that heavier women are more predisposed to breast cancer and less to osteoporosis, while thinner women are more predisposed to osteoporosis and less to breast cancer.

Not so, says a new study at Soroka Medical Center in Be’er Sheva in partnership with American cancer and bone specialists.

The preliminary findings, presented at an international conference on cancer research last week at Soroka, show that women with breast cancer are also more prone to bone fractures – even when they have high bone density and have not undergone treatments like chemotherapy that typically wear down the bones.

“From our point of view, this is a very fascinating finding,” Prof. Ethel Siris, director of the osteoporosis center at Columbia University Medical Center in New York, told Haaretz.

“What we’re thinking is that when you have breast cancer, even when it’s localized and not metastatic, there is something being produced or some signal being sent that must be impacting some aspect of bone formation that is affecting the quality of bone even before the quantity is reduced. And that’s why we’re seeing this fracturing.”

Machines that measure bone-mineral density are only able to gauge bone quantity, not quality, she said.

Siris, a former president of the U.S. National Osteoporosis Foundation, has been overseeing the study, which involves thousands of postmenopausal women residing in the Negev.

The study arose after Siris noticed that many of her female osteoporosis patients had breast cancer – and a colleague who specializes in breast cancer found that many of his patients had osteoporosis. “We knew there was something more complicated going on here, so we decided to do this study,” she said.

Soroka’s Dr. Merav Fraenkel, Siris’ main partner in the study, said it was long known that certain treatments for breast cancer such as chemotherapy and hormone therapy were bad for the bones. They were known to make patients more prone to fractures.

“We have observed that even women who don’t undergo these treatments and have a higher bone density have an increased risk of fracturing,” she said. This counters the assumption held by some that higher bone density protects breast cancer patients from fractures.

The immediate ramifications of the findings are that women with breast cancer need to be more vigilant about maintaining bone health, Siris said.

“If you’re a woman with breast cancer who has better bone density, that doesn’t mean you’re home free,” she said. “You should not ignore your bone health, and you need to do what you can to avoid a fracture. I mean, to go through all the things you go through with breast cancer and then end up breaking your hip is a nightmare.”

Prof. Larry Norton, deputy physician-in-chief for breast cancer programs at Memorial Sloan-Kettering Cancer Center in New York, is also involved in the Soroka study. According to Siris, Soroka was an obvious place to do the study because all women in the Negev with breast cancer are treated at this one center.

In addition, because almost all of them are insured by the same health fund, Clalit, it’s much easier for researchers to access their medical records.