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Bone density predicts risk of cancer

October 2, 2008 12:00:00 AM PDT
Bone scans are typically used to check for osteoporosis, but now researchers say they could be one of the most powerful predictors of breast cancer. At 64-years-old, two-time breast cancer survivor Ilya Sloan wonders this happened to her twice.

"We definitely ask these questions of ourselves. What did we do? Did we have a role in this?" asks Sloan.

University of Arizona researchers say results of a routine bone density test could provide an important clue in predicting breast cancer risk in older, post menopausal women.

"What we're showing in the study is that bone density may be an indicator or a marker of something else which may link to breast cancer risk," said Zhao Chen, Ph.D, MPH, University of Arizona epidemiologist.

An eight-year study of 10,000 post menopausal women looked at factors like age, race and history to estimate lifetime breast cancer risk -- and their hip-bone mineral density T-score. The finding -- older women with high bone density are twice as likely to develop breast cancer.

"High bone density is a marker of increased risk for breast cancer. We can use that piece of information to predict your breast cancer risk in the future," said Dr. Chen.

Researchers say combining a bone density score along with questionnaires and other risk assessment tool can give a clearer picture of a woman's actual breast cancer risk.

For Ilya, every new breast cancer study holds the promise for earlier intervention even prevention, and the hope that future generations won't have to go through what she did.

"That's the hope for my daughter and my granddaughter -- that we will be able to prevent and if it occurs, cure this disease," said Sloan.

One theory on this bone and breast connection is that more bone density often means more estrogen production. Researchers hope women this kind of information to make better decisions on how to reduce their breast cancer risk.

Web Extra Information: Bone Density Test for Breast Cancer

BACKGROUND:

The National Cancer Institute estimates that one in eight women in the United States will develop breast cancer in her lifetime. Next to skin cancer, breast cancer is the most common type of cancer among women. Because of the cancer's prevalence, numerous tools to predict a person's risk of breast cancer have been developed -- some as simple as answering questions and some as complex as genetic testing. One common tool used by professionals to assess a woman's risk of developing this type of cancer is the Gail test. It was developed by scientists at the National Cancer Institute and the National Surgical Adjuvant Breast and Bowel Project. The test is meant to be administered to women over age 35 and has only been validated in Caucasian women. It asks questions about factors like age, family history, race and personal health history. Although it is a valuable tool, experts say the Gail test shouldn't be used alone to determine cancer risk. One American Association for Cancer Research study found the test did not fully account for the association between breast density and calculated breast cancer risk. Study authors wrote that a measurement of breast density should be used in conjunction with the Gail test to assess a woman's risk for breast cancer.

ASSESSING THE RISK:

Although some breast cancer risk factors are simple to calculate -- like those found on the Gail test -- others are more complex and require the help of medical experts to determine. The American Cancer Society says women with an inherited mutation of the BRCA1 or BRCA2 gene have up to an 80 percent chance of developing breast cancer sometime in their life, and they are also more at risk of developing the cancer at a young age. These kinds of mutations are most often found in Jewish women of Eastern European origin and have also been found in African-American and Hispanic women. Genetic testing can be helpful in some situations to locate BRCA mutations, but the pros and cons should weighed. Another factor that contributes to a woman's risk of breast cancer is breast density. A recent study published in the Annals of Internal Medicine looked at 1.1 million women who had at least one mammogram in which breast density was measured and reported. Researchers also examined the women for other risk factors. They found that a risk prediction equation that includes breast density measurements accurately predicts breast cancer risk in some women, but is less accurate in other women. The American Cancer Society says women with dense breast tissue have more glandular tissue and less fatty tissue, as well as a higher risk of breast cancer. The density of breast tissue is best measured through a mammogram. It's important to keep in mind that having an abundance of risk factors doesn't necessarily mean a woman will develop breast cancer.

TWO BIRDS WITH ONE STONE:

Another health problem almost exclusive to women is osteoporosis, which has been linked to breast cancer in several ways. Research shows women who have had breast cancer treatment may be at increased risk for osteoporosis. This is mainly because chemotherapy reduces estrogen levels, and estrogen loss triggers bone loss. Another relationship between breast cancer and osteoporosis is a more positive one. Some osteoporosis medications have been shown to prevent, and even combat, breast cancer. Bisphosphonates, a class of osteoporosis medications, have shown to be successful in their ability to treat breast cancers that have spread to bone, and the medication raloxifene (Evista) has already been FDA approved to treat both the bone condition and prevent breast cancer in postmenopausal women at high risk of developing breast cancer.

 

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