Prevention of breast cancer in postmenopausal women: approaches to estimating and reducing risk.
BACKGROUND
It is uncertain whether evidence supports routinely estimating a postmenopausal woman's risk of breast cancer and intervening to reduce risk.


METHODS
We systematically reviewed prospective studies about models and sex hormone levels to assess breast cancer risk and used meta-analysis with random effects models to summarize the predictive accuracy of breast density. We also reviewed prospective studies of the effects of exercise, weight management, healthy diet, moderate alcohol consumption, and fruit and vegetable intake on breast cancer risk, and used random effects models for a meta-analyses of tamoxifen and raloxifene for primary prevention of breast cancer. All studies reviewed were published before June 2008, and all statistical tests were two-sided.


RESULTS
Risk models that are based on demographic characteristics and medical history had modest discriminatory accuracy for estimating breast cancer risk (c-statistics range = 0.58-0.63). Breast density was strongly associated with breast cancer (relative risk [RR] = 4.03, 95% confidence interval [CI] = 3.10 to 5.26, for Breast Imaging Reporting and Data System category IV vs category I; RR = 4.20, 95% CI = 3.61 to 4.89, for >75% vs <5% of dense area), and adding breast density to models improved discriminatory accuracy (c-statistics range = 0.63-0.66). Estradiol was also associated with breast cancer (RR range = 2.0-2.9, comparing the highest vs lowest quintile of estradiol, P < .01). Most studies found that exercise, weight reduction, low-fat diet, and reduced alcohol intake were associated with a decreased risk of breast cancer. Tamoxifen and raloxifene reduced the risk of estrogen receptor-positive invasive breast cancer and invasive breast cancer overall.


CONCLUSIONS
Evidence from this study supports screening for breast cancer risk in all postmenopausal women by use of risk factors and breast density and considering chemoprevention for those found to be at high risk. Several lifestyle changes with the potential to prevent breast cancer should be recommended regardless of risk.
Cummings
Steven R
SR
San Francisco Coordinating Center, California Pacific Medical Center Research Institute, 94107, USA. scummings@sfcc-cpmc.net
Tice
Jeffrey A
JA
Bauer
Scott
S
Browner
Warren S
WS
Cuzick
Jack
J
Ziv
Elad
E
Vogel
Victor
V
Shepherd
John
J
Vachon
Celine
C
Smith-Bindman
Rebecca
R
Kerlikowske
Karla
K
D000368:Aged; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage*; D014408:Biomarkers, Tumor / Q000097:blood; D001940:Breast / Q000473:pathology; D001943:Breast Neoplasms / Q000097:blood / Q000453:epidemiology / Q000209:etiology* / Q000473:pathology / Q000517:prevention & control*; D016022:Case-Control Studies; D016001:Confidence Intervals; D015986:Confounding Factors, Epidemiologic; D020847:Estrogen Receptor Modulators / Q000008:administration & dosage*; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood*; D006801:Humans; D008019:Life Style; D008875:Middle Aged; D015233:Models, Statistical; D016017:Odds Ratio; D017698:Postmenopause; D011237:Predictive Value of Tests; D011446:Prospective Studies; D020849:Raloxifene Hydrochloride / Q000008:administration & dosage; D016032:Randomized Controlled Trials as Topic; D012107:Research Design; D018570:Risk Assessment; D012307:Risk Factors; D040242:Risk Reduction Behavior; D013629:Tamoxifen / Q000008:administration & dosage
D018931:Antineoplastic Agents, Hormonal; D014408:Biomarkers, Tumor; D020847:Estrogen Receptor Modulators; D012739:Gonadal Steroid Hormones; D013629:Tamoxifen; D020849:Raloxifene Hydrochloride