Effect of raloxifene on the incidence of invasive breast cancer in postmenopausal women with osteoporosis categorized by breast cancer risk.
OBJECTIVE
To assess the effect of raloxifene, indicated for osteoporosis treatment and prevention, on invasive breast cancer in subgroups of postmenopausal women defined by risk factors for breast cancer.


METHODS
Data from the 4-year Multiple Outcomes of Raloxifene Evaluation (MORE) trial (N=7,705) and a follow-up study, the 4-year Continuing Outcomes Relevant to Evista (CORE) trial (N=4,011), were analyzed. Prespecified subgroups were defined by age (>or=65 versus<65 years), age at menopause (>or=49 versus<49 years), body mass index (>or=25 versus<25 kg/m2), family history of breast cancer (yes/no), serum estradiol level (5-10 versus<5, >10 versus<5 pmol/L), prior estrogen therapy (yes/no), and bone mass at MORE baseline, and 5-year predicted risk, assessed using the modified Gail model (>or=1.67 versus<1.67%), at CORE baseline. Time-to-first invasive breast cancer was analyzed using Cox proportional hazards models.


RESULTS
In the placebo group, older age, higher estradiol level, and a family history of breast cancer were associated with an increased breast cancer risk (P<0.05). Raloxifene therapy was associated with a reduced breast cancer risk in both women at lower and those at higher breast cancer risk. Hazard ratio point estimates were 0.11 to 0.67, corresponding to a 33% to 89% reduction in breast cancer risk with raloxifene versus placebo. The therapy by family history interaction was significant (P=0.04).


CONCLUSIONS
Raloxifene therapy was associated with a reduced risk of invasive breast cancer in postmenopausal women irrespective of the presence/absence of risk factors; its effect was greater in women with a family history of breast cancer.
Lippman
Marc E
ME
Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan 48109, USA. lippmanm@umich.edu
Cummings
Steven R
SR
Disch
Damon P
DP
Mershon
John L
JL
Dowsett
Sherie A
SA
Cauley
Jane A
JA
Martino
Silvana
S
D000368:Aged; D001943:Breast Neoplasms / Q000188:drug therapy* / Q000453:epidemiology / Q000517:prevention & control; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D015999:Multivariate Analysis; D009361:Neoplasm Invasiveness; D015663:Osteoporosis, Postmenopausal / Q000188:drug therapy* / Q000453:epidemiology; D010919:Placebos; D020849:Raloxifene Hydrochloride / Q000008:administration & dosage* / Q000627:therapeutic use; D016032:Randomized Controlled Trials as Topic / Q000706:statistics & numerical data; D012307:Risk Factors; D020845:Selective Estrogen Receptor Modulators / Q000008:administration & dosage* / Q000627:therapeutic use; D016896:Treatment Outcome
D010919:Placebos; D020845:Selective Estrogen Receptor Modulators; D020849:Raloxifene Hydrochloride