Susan G Komen  
I've Been Diagnosed With Breast Cancer Someone I Know Was Diagnosed Share Your Story Join Us And Stay Informed Donate To End Breast Cancer
Home > Understanding Breast Cancer > Breast Cancer Research > Table 6: Blood estrogen levels and the risk of breast cancer


Table 6: Blood estrogen levels and the risk of breast cancer


This summary table contains detailed information about research studies. Summary tables offer an informative look at the science behind many breast cancer guidelines and recommendations. However, they should be viewed with some caution. In order to read and interpret research tables successfully, it is important to understand some key concepts. Learn how to read a research table.

Introduction: Introduction: Estrogens are natural hormones that are important in sexual development and other body functions. They are produced mainly in the ovaries in premenopausal women, and mainly in fat tissue in postmenopausal women.  

Because of the different sources (and different levels) of estrogen in premenopausal and postmenopausal women, it is important to look at studies of estrogen and breast cancer risk by menopausal status.

Blood estrogen levels and breast cancer risk in postmenopausal women

The studies listed in the table below show that higher blood levels of the estrogen called estradiol increase the risk of breast cancer in postmenopausal women.

Blood estrogen and menopausal hormone therapy (postmenopausal hormone use)

All of the studies below excluded women who were using menopausal hormone therapy (MHT) at the time of blood collection. Certain MHT might mask the full effect natural blood estrogen levels have on breast cancer risk. By looking only at women who are not taking (or who have never taken) MHT, researchers may see more clearly how blood estrogen levels affect breast cancer risk.

Blood estrogen levels and breast cancer risk in premenopausal women

A pooled analysis of data from seven studies found that higher blood estrogen levels increased breast cancer risk in premenopausal women [1].

Learn more about blood estrogen levels and breast cancer risk.

Learn about 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: Prospective nested case-control studies with at least 100 breast cancer cases, pooled analyses and meta-analyses.

Table note: Relative risks above 1 indicate increased risk. Relative risks below 1 indicate decreased risk.

Risks related to total estradiol levels are shown in this table.  


Study Population
(number of participants)

Risk of Breast Cancer in Women with Higher Estradiol Levels
Compared to Women with Lower Estradiol Levels
Relative Risk (95%CI)



Nested case-control studies 





Nurses' Health Study [2]




2.1 (1.6-2.7)*

EPIC cohort [3-4]




2.58 (1.69-3.93) 




1.00 (0.66-1.52) 


New York University Women's Health Study [5]




2.06 (1.18-3.60)

PLCO [6]




1.75 (1.03-2.98)

Nurses' Health Study II [7]



1.2 (1.0-1.4)§ 


Falk et al. [8]




1.13 (0.63-2.01)

UK Collaborative Trial of Ovarian Cancer Screening [9]




1.15 (0.67-2.00)

Melbourne Collaborative Cohort Study [10]




1.44 (0.89-2.35)|| 

Study of Osteoporosis Fractures Research Group [11-12]




1.8 (0.9-3.6)¶  





2.9 (1.2-7.2)

ORDET cohort [13]




1.50 (0.88-2.54)

Pooled and meta-analyses 






EHBCCG [1,14]



1.41 (1.02-1.95)





2.00 (1.47-2.71)

Walker et al. [15]



1.14 (0.98-1.32)


Manjer et al. [16]




1.73 (1.04-2.88)

* Relative risk for estrogen receptor-positive and progesterone receptor-positive (ER+/PR+) breast cancers was 2.8 (2.0-4.0). Relative risk for estrogen and progesterone receptor-negative (ER-/PR-) breast cancers was 1.1 (0.6-2.1).

† Relative risk for ER+ cancers only. Relative risk for ER- breast cancers was 1.65 (0.91-2.98).

‡ High versus low levels of follicular estradiol in women at the same point in their menstrual cycle. Results for luteal estradiol levels were not statistically significant.

§ High versus low levels of follicular estradiol in women at the same point in their menstrual cycle. Results for luteal estradiol levels were similar with a relative risk 1.2 (1.0-1.6).

|| Relative risk for women with higher levels of free estradiol compared to women with lower levels of free estradiol was 1.75 (1.06-2.89).

¶ Relative risk for ER+ cancers only. Authors noted an increase in risk before adjustment for blood testosterone levels.



  1. Endogenous Hormones and Breast Cancer Collaborative Group. Sex hormones and risk of breast cancer in premenopausal women: a collaborative reanalysis of individual participant data from seven prospective studies. Lancet Oncol. 14(10):1009-19, 2013.
  2. Zhang X, Tworoger SS, Eliassen AH, Hankinson SE. Postmenopausal plasma sex hormone levels and breast cancer risk over 20 years of follow-up. Breast Cancer Res Treat. 137(3):883-92, 2013.
  3. James RE, Lukanova A, Dossus L, et al. Postmenopausal serum sex steroids and risk of hormone receptor-positive and -negative breast cancer: a nested case-control study. Cancer Prev Res (Phila). 4(10):1626-35, 2011.
  4. Kaaks R, Berrino F, Key T, et al. Serum sex steroids in premenopausal women and breast cancer risk within the European Prospective Investigation into Cancer and Nutrition (EPIC). J Natl Cancer Inst. 97(10):755-65, 2005.
  5. Zeleniuch-Jacquotte A, Shore RE, Koenig KL, Akhmedkhanov A, Afanasyeva Y, Kato I, Kim MY, Rinaldi S, Kaaks R, Toniolo P. Postmenopausal levels of oestrogen, androgen, and SHBG and breast cancer: long-term results of a prospective study. Br J Cancer. 90(1):153-9, 2004.
  6. Fuhrman BJ, Schairer C, Gail MH, et al. Estrogen metabolism and risk of breast cancer in postmenopausal women. J Natl Cancer Inst. 104(4):326-39, 2012.
  7. Fortner RT, Eliassen AH, Spiegelman D, Willett WC, Barbieri RL, Hankinson SE. Premenopausal endogenous steroid hormones and breast cancer risk: results from the Nurses' Health Study II. Breast Cancer Res. 2013 Mar 6;15(2):R19. [Epub ahead of print].
  8. Falk RT, Brinton LA, Dorgan JF, et al. Relationship of serum estrogens and estrogen metabolites to postmenopausal breast cancer risk: a nested case-control study. Breast Cancer Res. 2013 Apr 22;15(2):R34. [Epub ahead of print].
  9. Fourkala EO, Zaikin A, Burnell M, et al. Association of serum sex steroid receptor bioactivity and sex steroid hormones with breast cancer risk in postmenopausal women. Endocr Relat Cancer. 19(2):137-47, 2012.
  10. Baglietto L, Severi G, English DR, et al. Circulating steroid hormone levels and risk of breast cancer for postmenopausal women. Cancer Epidemiol Biomarkers Prev. 19(2):492-502, 2010.
  11. Cummings SR, Lee JS, Lui LY, Stone K, Ljung BM, Cauleys JA, for the Study of Osteoporosis Fractures Research Group. Sex hormones, risk factors, and risk of estrogen receptor-positive breast cancer in older women: a long-term prospective study. Cancer Epidemiol Biomarkers Prev. 14(5):1047-51, 2005.
  12. Cauley JA, Lucas FL, Kuller LH, et al. Elevated serum estradiol and testosterone concentrations are associated with a high risk for breast cancer. Ann Intern Med. 130(4):270-277, 1999.
  13. Sieri S, Krogh V, Bolelli G, et al. Sex hormone levels, breast cancer risk, and cancer receptor status in postmenopausal women: the ORDET cohort. Cancer Epidemiol Biomarkers Prev. 18(1):169-76, 2009.
  14. Walker K, Bratton DJ, Frost C. Premenopausal endogenous oestrogen levels and breast cancer risk: a meta-analysis. Br J Cancer. 105(9):1451-7, 2011.
  15. The Endogenous Hormones and Breast Cancer Collaborative Group. Endogenous sex hormones and breast cancer in postmenopausal women: reanalysis of nine prospective studies. J Natl Cancer Inst. 94(8): 606-616, 2002.
  16. Manjer J, Johansson R, Berglund G, Janzon L, Kaaks R, Agren A, Lenner P. Postmenopausal breast cancer risk in relation to sex steroid hormones, prolactin and SHBG (Sweden). Cancer Causes Control. 14(7):599-607, 2003.

Updated 10/31/13