Prevention check
Should I take a medicine to lower my breast cancer risk?
Tamoxifen, raloxifene and aromatase inhibitors can lower the chance of breast cancer in women at higher risk, but they have side effects. The US Preventive Services Task Force says who should be offered them. Check where you fall.
About you
For women. Nothing you enter leaves this page.
What you will see
Whether the USPSTF advice points to offering you a medicine to lower breast cancer risk.
Educational only, not medical advice. Talk to a clinician before starting any medicine.
Source
US Preventive Services Task Force, September 2019 recommendation on medication use to reduce risk of breast cancer.
Validated in
Women 35 or older without symptoms who have never had breast cancer or DCIS.
Limits
It does not calculate your breast cancer risk; it checks your answers against the USPSTF examples of increased risk. It does not cover women with a BRCA1/2 mutation or past chest radiation, or treatment after breast cancer.
What the USPSTF recommends
| Who | Recommendation | Grade |
|---|---|---|
| Women 35 or older at increased risk of breast cancer and at low risk of side effects | Clinicians should offer to prescribe a risk-reducing medicine such as tamoxifen, raloxifene or an aromatase inhibitor | B |
| Women 35 or older not at increased risk | Against routine use of these medicines | D |
The USPSTF is working on an update of this topic, but no draft has been posted, so the 2019 recommendation stands (USPSTF 2019).
Who counts as increased risk
There is no single cutoff. Clinicians can use a risk tool or look at risk factors. The USPSTF does not endorse one tool, but names the National Cancer Institute Breast Cancer Risk Assessment Tool and the Breast Cancer Surveillance Consortium Risk Calculator as publicly available tools tested in US women. Women with a 5-year risk of at least 3% are likely to gain more than they lose from these medicines (USPSTF 2019).
Examples of combinations that mean increased risk include (USPSTF 2019):
- age 65 or older with one first-degree relative (mother, sister or daughter) who had breast cancer;
- age 45 or older with more than one first-degree relative with breast cancer, or one diagnosed before 50;
- age 40 or older with a first-degree relative who had cancer in both breasts;
- atypical ductal or lobular hyperplasia or lobular carcinoma in situ on a past biopsy.
Women younger than 60 with no other risk factors, or with a low 5-year risk, are given as examples of women not at increased risk (USPSTF 2019). The tools predict how many women in a group will get breast cancer well, but are only modest at telling which individual women will (USPSTF 2019).
Benefits and side effects
| Medicine | Fewer invasive breast cancers over 5 years, vs placebo | Main side effects |
|---|---|---|
| Tamoxifen | 7 per 1,000 women | Blood clots (more than raloxifene), endometrial cancer in women with a uterus, cataracts, hot flashes |
| Raloxifene | 9 per 1,000 women | Blood clots, hot flashes |
| Aromatase inhibitors | 16 per 1,000 women | Hot flashes, stomach symptoms, muscle and joint pain, a possible rise in stroke and other heart and blood vessel events; they do not lower and may raise fracture risk |
These figures come from trials with different women, so the medicines cannot be ranked from them. In the STAR trial, which compared tamoxifen with raloxifene directly, tamoxifen lowered risk more over long follow-up. The benefit is likely larger for women with a 5-year risk of 3% or more (USPSTF 2019). The medicines lower the risk of estrogen receptor–positive breast cancer (USPSTF 2019). Tamoxifen and raloxifene also lower the risk of some fractures (USPSTF 2019).
Side effects such as blood clots are more likely in older women. Women who have had a hysterectomy do not face the endometrial cancer risk from tamoxifen (USPSTF 2019).
Which medicine, and for how long
Only tamoxifen is indicated to lower breast cancer risk before menopause. Raloxifene and aromatase inhibitors are for women after menopause (USPSTF 2019). In trials, women took the medicines for 3 to 5 years. The benefit of tamoxifen lasted up to 8 years after stopping, while its extra risk of blood clots and endometrial cancer went back to baseline (USPSTF 2019).
Common questions
I have a BRCA mutation. Does this apply to me?
Women with a BRCA1 or BRCA2 mutation, or who had chest radiation when young, are at especially high risk. By age 80 about 72% of women with a BRCA1 mutation and 69% with a BRCA2 mutation develop breast cancer. The USPSTF did not find enough evidence on medicines for these women and leaves their care to other organizations (USPSTF 2019). The BRCA family history check shows who the USPSTF advises to have genetic counseling.
How often should risk be checked again?
There is no set interval. The USPSTF suggests checking again when risk factors change, for example when a family member is diagnosed with breast cancer or a biopsy finds atypical cells (USPSTF 2019).
Do many women take these medicines?
Not many. One analysis found that about 16% of women at increased risk used them, and many women weighing the choice worry mostly about side effects (USPSTF 2019). The USPSTF asks clinicians to talk through each woman's values and preferences as well as her risk (USPSTF 2019).
Also see the breast cancer screening check, the BRCA family history check, the menopause hormone therapy check and all screening tests by age.
Sources
- US Preventive Services Task Force. Medication Use to Reduce Risk of Breast Cancer: US Preventive Services Task Force Recommendation Statement. JAMA. 2019;322(9):857-867. www.uspreventiveservicestaskforce.org/uspstf/recommendation/breast-cancer-medications-for-risk-reduction
Written and maintained by the uncovermyrisk.com editorial team. We do not have a medical reviewer; every claim links to its primary source above. Last reviewed: 2026-10-29. Spotted an error? See About.