Breast cancer and bone mass in older women: is bone density prescreening for mammography useful?

INTRODUCTION: The utility of screening mammography for older women with low bone mineral density (BMD) is controversial. This case-control study compares BMD at multiple sites in women with and without breast cancer to determine if BMD prescreening is useful in selecting women for continued screening mammograms.
METHODS: Women diagnosed with breast cancer in the preceding 4 months and age-matched controls (+/-2 years) with a normal mammogram, all aged 65 years and older, were recruited on a 1:2 basis; 237 women participated: 79 women (cases) with breast cancer and 158 controls. BMD at the lumbar spine, hip, radius, and whole body was measured with dual x-ray absorptiometry (DXA).
RESULTS: Among women with breast cancer, 17.1% had stage 0, 41.5% stage I, 40.0% stage II, and 1.4% stage III. Women with breast cancer had larger waist circumferences (p=0.002) and waist-hip ratios (p=0.01), and they exercised less (p=0.002) than women of the control group. However, there were no differences between the cases and controls for age, obesity, and reproductive and menopausal history variables, or other covariates (p>0.10). There were no differences in lumbar spine, total hip, femoral neck, midshaft radius, or total body BMD (p>0.10), although the cases had higher BMD at the ultradistal radius than the controls (means: 0.527 vs. 0.516, respectively; p=0.014). There were no differences in breast cancer risk by tertile of BMD or osteoporosis status at the hip or spine.
CONCLUSION: There is little difference in BMD between women with and without breast cancer. BMD is not useful as a prescreening predicator of mammography in older women and using it as such would result in cases of breast cancer being missed.