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

Abstract

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. 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). 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. 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.