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Home > Understanding Breast Cancer > Breast Cancer Research > Table 29: The use of tamoxifen and raloxifene to reduce the risk of breast cancer

  


Table 29: The use of tamoxifen and raloxifene to reduce 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: Tamoxifen and raloxifene are the only two drugs FDA-approved to lower the risk of breast cancer in women who do not have breast cancer but are at high risk. The use of risk-lowering drugs may also be called chemoprevention, although no chemotherapy is involved.

Both tamoxifen and raloxifene can lower the risk of invasive breast cancer (tamoxifen by about 50 percent and raloxifene by about 38 percent) in women at high risk* [1]. Both drugs also lower the risk of non-invasive breast cancer, such as ductal carcinoma in situ (DCIS), in women at high risk [1].

Tamoxifen and raloxifene only reduce the risk of estrogen receptor-positive breast cancers. Neither drug reduces the risk of estrogen receptor-negative cancers.

Tamoxifen

Both pre- and postmenopausal women can take tamoxifen.

Tamoxifen is related to some health risks and is not recommended for all women [1-2]. Learn more about the health risks of tamoxifen.  

Raloxifene

Only postmenopausal women can take raloxifene. It is not given to premenopausal women.

Raloxifene has fewer harmful side effects than tamoxifen and may be a better choice for some women [1]. Learn more about the health risks of raloxifene.

*High risk is defined as having a 1.67 percent or greater chance of getting breast cancer in the next five years, as calculated by the Breast Cancer Risk Assessment Tool (the Gail model) [3]. Learn more about the Breast Cancer Risk Assessment Tool.  

Study selection criteria: Randomized controlled trials with at least 500 participants, 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)
 

 
 Follow-up
(years)
 

Absolute Risk of
Invasive Breast Cancer
(number of cases per 1,000 women)
 

Relative Risk of Invasive Breast Cancer
in Women Taking Tamoxifen
Compared to
Women Taking Placebo
RR (95% CI)  
 

 Among Women Taking Tamoxifen 

Among Women Taking Placebo 

Randomized controlled trials of tamoxifen versus placebo 

NSABP P-1 (National Surgical Adjuvant Breast and Bowel Project) [2]

13,388 women
aged 35 and over,
at high risk

7

25 per 1,000

43 per 1,000

0.57
(0.46-0.70)

IBIS-I Trial (International Breast Cancer Intervention Study) [4]

7,154 women
aged 35 to 70,
at high risk

8

55 per 1,000

40 per 1,000

0.73
(0.58-0.91)

Italian Tamoxifen Prevention Study [5]

5,408 women
aged 35-70,
who had hysterectomy

11

23 per 1,000

27 per 1,000

0.84
(0.60-1.17)

Royal Marsden Hospital, UK [6]

2,471 women
aged 30-70,
with a family history of breast cancer

13

84 per 1,000

66 per 1,000

0.78
(0.58-1.04)

Study 

Study Population
(number of participants)
 

 Follow-up
(years)
 

 Absolute Risk of
Invasive Breast Cancer
(number of cases per 1,000 women)
 

Relative Risk of Invasive Breast Cancer
in Women Taking Tamoxifen
Compared to
Women Taking Placebo
RR (95% CI)
 

 Among Women Taking Raloxifene 

 Among Women Taking Placebo 

Randomized controlled trials of raloxifene versus placebo 

MORE Trial (Multiple Outcomes for Raloxifene Evaluation) [7]

7,705 postmenopausal women
with osteoporosis

4

1 per 1,000

5 per 1,000

0.28
(0.17-0.46)

CORE Trial (Continuing Outcomes Relevant to Evista) [8]

5,213 postmenopausal women
with osteoporosis

4*

2 per 1,000

5 per 1,000

0.41
(0.24-0.71) 

RUTH (Raloxifene Use for The Heart) trial [9]

10,101 postmenopausal women
with heart disease or
at risk for heart disease

6

8 per 1,000

14 per 1,000

 0.56
(0.38-0.83)

Study 

Study Population
(number of participants)
 

 Follow-up
(years)
 

Absolute Risk of
Invasive Breast Cancer
(number of cases per 1,000 women)
 

 Relative Risk of Invasive Breast Cancer
in Women Taking Raloxifene Compared to Women Taking Tamoxifen
RR (95% CI)
 

 Among Women Taking Raloxifene 

 Among Women Taking Tamoxifen 

Randomized controlled trials of raloxifene versus tamoxifen 

NSABP/STAR P-2 (National Surgical Adjuvant Breast and Bowel Project/Study of Tamoxifen and Raloxifene) [1]

19,490 postmenopausal women
at high risk

7

5 per 1,000

4 per 1,000

1.24
(1.05-1.47)

Study 

Number of Participants or Studies in Analysis  

Drug Studied 

Relative Risk of Invasive Breast Cancer
in Women Taking Tamoxifen or Raloxifene
Compared to Women Taking Placebo
RR (95% CI)
 

Pooled and meta-analyses of tamoxifen or raloxifene versus placebo  

Cuzick et al. [10]

83,399

Tamoxifen

0.67
(0.59-0.76)

   

Raloxifene

0.66
(0.55-0.80)

Nelson et al. [11]

4 studies

Tamoxifen

0.70
(0.59-0.82)

 

2 studies

Raloxifene

0.44
(0.27-0.71)

* In addition to years in the MORE trial. 

References 

  1. Vogel VG, Costantino JP, Wickerham DL, et al. for the National Surgical Adjuvant Breast and Bowel Project. Update of the National Surgical Adjuvant Breast and Bowel Project Study of Tamoxifen and Raloxifene (STAR) P-2 Trial: Preventing breast cancer. Cancer Prev Res. 3(6):696-706, 2010.
  2. Fisher B, Costantino JP, Wickerham DL, et al. Tamoxifen for Prevention of Breast Cancer: Current Status of the National Surgical Adjuvant Breast and Bowel Project P-1 Study. J Natl Cancer Inst. 97(22):1652-62, 2005.
  3. Gail MH, Brinton LA, Byar DP, et al. Projecting individualized probabilities of developing breast cancer for white females who are being examined annually. J Natl Cancer Inst. 81(24):1879-1886, 1989.
  4. Cuzick J, Forbes JF, Sestak I, et al. for the International Breast Cancer Intervention Study I (IBIS-I) Investigators. Long-term results of tamoxifen prophylaxis for breast cancer—96-month follow-up of the randomized IBIS-I trial. J Natl Cancer Inst. 21;99(4):272-82, 2007.
  5. Veronesi U, Maisonneuve P, Rotmensz N, et al. for the Italian Tamoxifen Study Group. Tamoxifen for the prevention of breast cancer: late results of the Italian Randomized Tamoxifen Prevention Trial among women with hysterectomy. J Natl Cancer Inst. 99(9):727-37, 2007.
  6. Powles T, Ashley S, Tidy A, Smith IE, Dowsett M. Twenty-year follow-up of the Royal Marsden randomized, double-blinded tamoxifen breast cancer prevention trial. J Natl Cancer Inst. 99(4):283-90, 2007.
  7. Cauley JA, Norton L, Lippman ME et al. Continued breast cancer risk reduction in postmenopausal women treated with raloxifene: 4-year results from the MORE trial. Breast Cancer Res Treat. 65(2):125-143, 2001.
  8. Martino S, Cauley JA, Barrett-Connor E, et al. for the CORE Investigators. Continuing Outcomes Relevant to Evista: breast  cancer incidence in postmenopausal osteoporotic women in a randomized trial of raloxifene. J Natl Cancer Inst. 96(23):1751-1761, 2004.
  9. Barrett-Connor E, Mosca L, Collins P, et al. Effects of raloxifene on cardiovascular events and breast cancer in postmenopausal women. N Engl J Med. 355(2):125-37, 2006.
  10. Cuzick J, Sestak I, Bonanni B, et al. for the SERM Chemoprevention of Breast Cancer Overview Group. Selective oestrogen receptor modulators in prevention of breast cancer: an updated meta-analysis of individual participant data. Lancet. 381(9880):1827-34, 2013.
  11. Nelson HD, Fu R, Griffin JC, Nygren P, Smith ME, Humphrey L. Systematic review: Comparative effectiveness of medications to reduce risk for primary breast cancer. Ann Intern Med. 151(10):703-715, 2009.

 Updated 01/13/14