| This summary table contains detailed information about research studies. While viewing summary tables offers an informative glimpse at the science behind many breast cancer guidelines and recommendations, they should be viewed with some caution. There are a number of concepts you must understand to be able to successfully read and interpret research tables. To get some background information about understanding research tables, please see How to Read a Research Table. |
Introduction: There is solid evidence that breastfeeding can lower the risk of breast cancer. Two large analyses that combined the results from many studies found that women who breastfed had a lower risk of breast cancer compared to those who had not [1,2]. And, a meta-analysis of five case-control studies found that breastfeeding reduced the risk of ER+/PR+ and ER-/PR- breast cancers [3].
Find more information on the strengths and weaknesses of different types of studies.
See how this risk factor compares with other risk factors for breast cancer.
Study selection criteria: Latest pooled and meta-analyses.
Table note: Relative risk above 1 indicates increased risk. Relative risk below 1 indicates decreased risk.
| |
Study
|
Study Population
(number of participants)
|
Relative Risk of Breast Cancer in Women Who Have Breastfed Compared to Women Who Have Not, RR (95% CI)
|
Premenopausal
|
Postmenopausal
|
Pooled and Meta-analyses
|
Bernier et al. [1]*
|
70,777
|
0.76 (0.66-0.87)
|
0.83 (0.68-1.01)
|
CGHFBC [2]†
|
147,275
|
0.94‡ Sig
|
Sig = Statistically significant.
* Only case-control studies.
† Includes all case-control studies, and some, but not all, major cohort studies: for those not included, the combined RR for ever versus never having breastfed was 0.93 (0.87-1.00).
‡ For one year duration of breastfeeding.
References
1. Bernier MO, Plu-Bureau G, Bossard N, et al. Breast feeding and risk of breast cancer: a meta-analysis of published studies. Human Reproduction Update. 6(4):374-386, 2000.
2. Collaborative Group on Hormonal Factors in Breast Cancer. Breast cancer and breast feeding: collaborative reanalysis of individual data from 47 epidemiological studies in 30 countries, including 50,302 women with breast cancer and 96,973 women without the disease. Lancet 20:187-195, 2002.
3. Ma H, Bernstein L, Pike MC, Ursin G. Reproductive factors and breast cancer risk according to joint estrogen and progesterone receptor status: a meta-analysis of epidemiological studies. Breast Cancer Res. 19;8(4):R43, 2006.
Updated 09/04/09
