***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Aim To determine the contribution of bone mineral density ( BMD ) to breast cancer risk relative to other established breast cancer risk factors in postmenopausal women with osteoporosis . Methods Data for this analysis comprised those collected from women r and omized to placebo in the MORE and CORE trials ( N = 2,576 ) . Risk factors measured at baseline included age , family history of breast cancer , estradiol level , body mass index , prior hormone therapy , BMD and vertebral fracture status . Cox proportional hazards regression models were used to calculate the hazard ratios ( HRs ) and 95 % confidence intervals ( CIs ) . Results Over a total of 13,698 woman-years of follow-up , 65 incident breast cancers occurred . In univariate analyses , older age and family history of breast cancer were the strongest predictors of breast cancer risk , associated with a 2.4- and 2.6-fold increase in breast cancer incidence . A higher estradiol level was associated with a 1.9-fold increase in breast cancer incidence . The association between femoral neck BMD and breast cancer incidence was only significant after adjustment for age ( P = 0.03 ) . The final multivariable model included age , family history , estradiol , BMD  , and the BMD-estradiol interaction since the effect of BMD on breast cancer varied by estradiol level ( interaction P-value , 0.04 ) ; in those with a lower estradiol level , a higher BMD was associated with a 2.6-fold increased in breast cancer . Conclusion Overall , BMD is a relatively weak predictor of breast cancer risk in these postmenopausal women with osteoporosis , after taking into consideration age , family history and endogenous estradiol level Study objective : Older women with high bone mineral density ( BMD ) have an increased risk of breast cancer but it is not well known whether this association is associated with the stage of the tumor . The objective of the study is to determine if older women with high BMD are likely to develop a more aggressive form of breast cancer , as defined by mortality . Patients : We prospect ively studied 1504 women who were 75 years of age or older at the entry in the study ( range , 75–90 years ) , between 1992 and 1994 .  BMD was measured by dual-photon X-ray absorptiometry at three skeletal sites ( trochanter , Ward 's triangle , femoral neck ) . The women were followed for a mean of 7 years for the occurrence of breast cancer . Cox proportional-hazards models were used to obtain estimates of the relative risk of breast cancer and relative risk of death according to the BMD . Main results : Forty-five incident breast cancer cases were identified . In multivariate analyses of the risk of breast cancer for women in the highest tertile of BMD was greater than for women in the lowest tertile . Indeed , the women with a trochanter BMD in the highest tertile were at 2.3-fold increased risk compared with women in the lowest tertile . The women with highest tertile BMD measured at the Ward 's triangle and at the femoral neck were respectively at 2.2- and 3.3-fold increased risk compared with women at the lowest risk . The 7-year survival rates were markedly less favorable for women in the second and third tertile of the three skeletal sites compared with the lowest tertile . The risk of death was greater for women in the highest tertile of BMD than for women in the lowest tertile at every skeletal site . Conclusion : Elderly women with high BMD have an increased risk of breast cancer , especially advanced cancer , compared with women with low BMD A total of 489 elderly women aged 65 - 75 yr who participated in a 3-yr , r and omized , blinded osteoporosis trial underwent measurements of  serum estradiol , bioavailable estradiol , and SHBG .  At baseline , bone mineral density ( BMD ) was lower at the femoral sites ( 7 - 19 % , P < 0.05 ) , total body ( 6 - 8 % , P < 0.05 ) , and spine ( 5 - 9 % , P = 0.2 ) in women in the lowest tertile for serum total estradiol [ < 9 pg/ml ( 33 pmol/liter ) ] , serum bioavailable estradiol [ < 2.4 pg/ml ( 8.8 pmol/liter ) ] , or highest tertile for serum SHBG ( > 165 nmol/liter ) , compared with women in the highest tertiles of total estradiol [ > 13.3 pg/ml ( 49 pmol/liter ) ] and bioavailable estradiol [ > 4 pg/ml ( 14 pmol/liter ) ] or lowest tertile for SHBG ( < 113 nmol/liter ) . Bone markers were increased in women in the lowest tertile for serum total estradiol ( not significant ) and bioavailable estradiol ( P < 0.05 ) and highest tertile for SHBG ( P < 0.05 ) . In the longitudinal study , the rate of bone loss in the placebo group was significantly higher in total body ( P < 0.05 ) and spine ( P < 0.05 ) in women in the lowest tertile , compared with the highest tertile of serum bioavailable estradiol . After treatment with conjugated equine estrogens 0.625 mg/d , the increase in BMD was 4 - 6 % higher at the femoral sites ( P < 0.05 ) , total body ( P < 0.05 ) , and spine ( not significant ) , in the lowest tertile , compared with the highest tertile of serum bioavailable estradiol or highest tertile , compared with the lowest tertile of serum SHBG . In summary , small variations in endogenous serum estradiol and high serum SHBG determine differences in BMD and rate of bone loss in elderly women and also affect the response to treatment with estrogen . Women with a serum estradiol level of less than 9 pg/ml ( 33 pmol/liter ) are optimal c and i date s for estrogen therapy for osteoporosis prevention ABSTRACT Objective : To evaluate the relationship between bone mass and risk of breast cancer and to determine the effect of raloxifene therapy on breast cancer incidence in women categorized by bone mass into low bone mass and osteoporosis subgroups . Design : In this post hoc analysis , data were analyzed from the Multiple Outcomes of Raloxifene Evaluation ( MORE ) trial , enrolling postmenopausal women with low bone mass ( N = 7705 ) , and the Continuing Outcomes Relevant to Evista ( CORE ) trial , a follow-up to MORE enrolling 4011 MORE participants . Total follow-up was for up to 8 years . Women with a total hip bone mineral density ( BMD ) T-score < –1 to > –2.5 or T-score ≤ –2.5 ( referent , NHANES III data base ) were classified as having low bone mass or osteoporosis , respectively . Women with a pre-existing vertebral fracture were considered as having osteoporosis irrespective of BMD T-score . Analyses were performed for invasive breast cancers and invasive estrogen-receptor ( ER ) positive breast cancers . Results : Women with low bone mass ( N = 3829 ) had a twofold higher incidence of invasive ER-positive breast cancer than those with osteoporosis ( N = 3836 ) ( HR 2.13 , 95 % CI 1.12–4.03 ) . The incidence of all invasive breast cancers did not differ significantly between the bone mass groups . The incidences of invasive and invasive ER-positive breast cancers were 65–78 % lower in women assigned raloxifene versus placebo in both the low bone mass and osteoporosis groups ( p < 0.05 ) . Conclusions : In this post hoc analysis of postmenopausal women participating in MORE and CORE , bone mass was a predictor of invasive ER-positive breast cancer  . Raloxifene treatment reduced the risk of invasive and invasive ER-positive breast cancers in women with low bone mass and those with osteoporosis . Since participants were older postmenopausal women with low bone mass , whether these findings can be generalized to other postmenopausal women is unclear Summary In this prospect i ve study in 2,137 perimenopausal and early postmenopausal women who were followed over a 13.1-year period of time , we observed no association between bone mineral density measured at the beginning of menopause and the subsequent risk of breast cancer . Introduction This study aim ed to investigate the relationship between BMD and the risk of breast cancer ( BC ) in young postmenopausal women . Methods As part of a clinical research program , 2,137 women who were perimenopausal or within their 5 first postmenopausal years were scanned  between 1988–1990 and review ed on average 13.1 years after their initial examination . Ninety-eight incident BC cases were recorded throughout the follow-up . Results Women with incident BC significantly differed from those who had never had BC with regard to age at menarche , age of birth of 1st child , familial history of BC and postmenopausal hormone therapy ( PHT ) use . There was no significant difference between the two groups for baseline DXA of the spine . There was a trend for BC cases for having lower femoral neck BMD compared to women without BC . However , women with low BMD were more likely to have taken PHT by the end of the study . In Cox multivariate analyses the relationship between BC risk and femoral neck BMD no longer existed . Conclusions There was no relationship between BMD measured within the first postmenopausal years and the risk of BC , which makes unlikely the possibility of using BMD as a predictor factor for BC in early postmenopausal women OBJECTIVE To test the hypothesis that bone  mineral density ( BMD ) is associated with the risk of developing breast cancer in older women . DESIGN Prospect i ve cohort study with mean ( SD ) follow-up of 3.2 ( 1.6 ) years . SETTING Four clinical centers , one each located in the following areas : Baltimore , Md ; Minneapolis , Minn ; Portl and , Ore ; and the Monongahela Valley in Pennsylvania . PARTICIPANTS A total of 6854 nonblack women who were 65 years of age or older and enrolled in the Study of Osteoporotic Fractures . MEASUREMENTS  Radius and calcaneus BMD  by single photon absorptiometry at baseline ; hip and spine BMD  by dual-energy x-ray absorptiometry 2 years later . MAIN OUTCOME MEASURE Breast cancer confirmed by medical record review . RESULTS A total of 97 women developed breast cancer . In the multivariate model , adjusting for age , the degree of obesity , and other important covariates , the risk of breast cancer was about 30 % to 50 % higher per 1 SD increase in BMD ( relative risk , distal radius BMD=1.50 ; 95 % confidence interval , 1.16 - 1.95 ) . The age-adjusted incidence rate of breast cancer per 1000 person-years among women in the lowest quartile of distal radius BMD was 2.46 , compared with 5.99 among women with the highest BMD . Women with BMD above the 25th percentile were at 2.0 to 2.5 times increased risk of breast cancer compared with women below the 25th percentile . Results were consistent across all BMD sites . CONCLUSIONS Bone mineral density predicts the risk of breast cancer in older women . The magnitude of the association is similar to that observed between BMD and all fractures . Our findings suggest a link between 2 of the most common conditions affecting a woman 's health . Identifying a common denominator for these conditions should substantially improve our underst and ing of their etiology and prevention Objective : This case – cohort study was design ed to examine whether total hip bone mineral density ( BMD ) is independently associated with breast cancer over and above its association with other determinants , including levels of total and bioavailable estradiol and testosterone and sex-hormone binding globulin . Methods : Our study population was selected from a cohort of 8203 postmenopausal women who were screened for the Fracture Intervention Trial in 1992 , at which time  BMD was assessed  , and  blood sample s were obtained . A total of 109 women developed breast cancer during four years of follow-up ; 173 other r and omly selected women from the larger cohort were also selected . Cox proportional hazards with robust variance adjustment was used for these analyses . Results : Relative to women in the lower fourth of the BMD distribution , the risk associated with being in the upper fourth was 2.6 ( 95 % confidence interval ( CI ) 1.1–5.8 ) . After adjusting for serum hormone levels , the corresponding relative risk was 2.5 ( 95 % CI 0.9–5.2 ) . With body mass index and number of years since menopause added to the multivariate analysis , the relative risk decreased to 1.4 ( 95 % CI 0.5–4.0 ) . Conclusions : BMD may not influence breast cancer risk independent of its relationship with endogenous hormones and measured covariates 
    Output:
    
Furthermore , the results of the dose – response analysis did not show a significant association between BMD at the lumbar spine , femoral neck , or total hip and the risk of BC .
Conclusion There is no relationship between BMD and the risk of BC .