Reproductive history in relation to breast cancer risk among Hispanic and non-Hispanic white women.
OBJECTIVE
To evaluate reproductive history risk factors in breast cancer among Hispanic (HISP) women in the U.S. southwest, a population with approximately 33% lower breast cancer incidence than non-Hispanic whites (NHW).


METHODS
Population-based case-control study of HISP (796 cases, 919 controls) and NHW (1,525 cases, 1,596 controls) women.


RESULTS
19.3% of HISP women reported five or more births and had a reduced risk of breast cancer, adjusted odds ratio (OR) 0.70 (95% confidence interval (CI): 0.50, 0.98) compared to those with one or two births. Breast cancer risk for HISP increased with older age at first birth, p trend = 0.008. Parity and age at first birth associations were specific to ER positive tumors. HISP women who had given birth within five years had higher breast cancer risk than women with 16-25 years since a birth, OR 2.62 (95% CI: 1.44, 4.78); the trend with years since last birth was stronger than for NHWs, p interaction = 0.05.


CONCLUSIONS
Reproductive history influences on breast cancer risk among HISP were similar to associations reported for NHWs. Differences in the prevalence of reproductive risk factors would explain an estimated 6.6% lower breast cancer incidence for HISP compared to NHWs.
Sweeney
Carol
C
Division of Epidemiology, University of Utah, 30 N 1900 E, AC230, Salt Lake City, Utah 841032, USA. carol.sweeney@hsc.utah.edu
Baumgartner
Kathy B
KB
Byers
Tim
T
Giuliano
Anna R
AR
Herrick
Jennifer S
JS
Murtaugh
Maureen A
MA
Slattery
Martha L
ML
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000208:ethnology*; D044584:Carcinoma, Ductal / Q000208:ethnology*; D018275:Carcinoma, Lobular / Q000208:ethnology*; D016022:Case-Control Studies; D016001:Confidence Intervals; D005260:Female; D006630:Hispanic or Latino / Q000706:statistics & numerical data*; D006801:Humans; D008875:Middle Aged; D015995:Prevalence; D017584:Reproductive History; D012307:Risk Factors; D015206:Southwestern United States / Q000453:epidemiology