Reproductive Factors and Breast Cancer Subtypes
Author Information
Author(s): G. Ursin, L. Bernstein, S. J. Lord, R. Karim, D. Deapen, M. F. Press, J. R. Daling, S. A. Norman, J. M. Liff, P. A. Marchbanks, S. G. Folger, M. S. Simon, B. L. Strom, R. T. Burkman, L. K. Weiss, S. R. Spirtas
Primary Institution: Keck School of Medicine, University of Southern California
Hypothesis
Reproductive factors may provide differential protection against breast cancer subtypes defined by hormone receptor status.
Conclusion
High parity and early age at first birth reduce the risk of receptor-positive breast tumors, while breastfeeding lowers the risk for both receptor-positive and receptor-negative tumors.
Supporting Evidence
- Multiparity and early age at first birth were associated with reduced risk of ER + PR + tumors.
- Duration of breastfeeding was associated with lower risk of both receptor-positive and receptor-negative tumors.
- Results were consistent across different age and ethnicity subgroups.
Takeaway
Having more children and having them at a younger age can help lower the risk of certain types of breast cancer, and breastfeeding is good for reducing the risk of all types.
Methodology
The study used a multicenter case-control design, analyzing data from the NIHCD Women's Contraceptive and Reproductive Experiences (CARE) Study.
Potential Biases
Potential bias due to missing ERPR status and variations in assessment methods across laboratories.
Limitations
ERPR status was not available for all cases, and the methods for assessing receptor status may have varied by laboratory.
Participant Demographics
The study included White and African-American women aged 35-64 from five US regions.
Statistical Information
P-Value
0.0001
Confidence Interval
0.59–0.81
Statistical Significance
p<0.05
Digital Object Identifier (DOI)
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