Medicines to lower breast cancer risk
For women 35 and older at increased risk of breast cancer and at low risk of side effects, the USPSTF recommends that clinicians offer a medicine to lower that risk, such as tamoxifen, raloxifene or an aromatase inhibitor (grade B, 2019). For women not at increased risk, it recommends against routine use (grade D). (USPSTF, 2019)
These medicines have real side effects, including blood clots, so they are for women whose risk is high enough to outweigh them. The advice does not apply to women who have or had breast cancer or DCIS. (USPSTF, 2019) Your doctor can estimate your risk and talk through the trade-offs.
- USPSTF grade
- B (increased risk), D (not)
- Who
- Women at increased risk
- Ages
- 35 and older
- Medicines
- Tamoxifen, raloxifene, aromatase inhibitors
Who it is for, by risk
| Women 35 and older | USPSTF grade | What it means |
|---|---|---|
| At increased risk and at low risk of side effects | B | Offer a risk-reducing medicine |
| A 5-year breast cancer risk of 3% or more | B | More likely to get more benefit than harm; offer if the risk of harms is low |
| Not at increased risk, such as under 60 with no added risk factors | D | Do not use routinely; the harms likely outweigh the benefit |
There is no single cutoff for increased risk. Clinicians can use a risk tool, such as the National Cancer Institute Breast Cancer Risk Assessment Tool or the Breast Cancer Surveillance Consortium calculator, or combinations of risk factors. One example the USPSTF gives is age 65 or older with one first-degree relative who had breast cancer. (USPSTF, 2019)
Risk is worth checking again when it changes, for example when a family member is diagnosed with breast cancer or a biopsy finds atypical hyperplasia or lobular carcinoma in situ. (USPSTF, 2019)
The medicines and their harms
| Medicine | Who can use it | Main harms |
|---|---|---|
| Tamoxifen | Before or after menopause | Blood clots, endometrial cancer in women with a uterus, cataracts, hot flashes |
| Raloxifene | After menopause only | Blood clots (less than tamoxifen), hot flashes |
| Aromatase inhibitors | After menopause only | Hot flashes, stomach and bowel symptoms, muscle and joint pain |
The harms of tamoxifen and raloxifene are greater in older women. Women who have had a hysterectomy are not at risk of endometrial cancer from tamoxifen. (USPSTF, 2019)
What other groups say
As summarized by the USPSTF, the American Society of Clinical Oncology (2013) recommended discussing tamoxifen with women 35 and older at increased risk, and raloxifene and exemestane after menopause. The National Comprehensive Cancer Network recommends these medicines from 35: only tamoxifen before menopause, and tamoxifen, raloxifene, anastrozole or exemestane after. These broadly agree with the USPSTF. (USPSTF, 2019)
Questions people ask
Who should take tamoxifen to prevent breast cancer?
The USPSTF recommends that clinicians offer a risk-reducing medicine, such as tamoxifen, to women 35 and older at increased risk of breast cancer and at low risk of side effects. Women with a 5-year risk of 3% or more are more likely to benefit. (USPSTF, 2019)
Should women at average risk take these medicines?
No. The USPSTF recommends against routine use for women not at increased risk (grade D), because the harms likely outweigh the benefit. (USPSTF, 2019)
Does a BRCA gene change mean I should take one?
A family history linked to BRCA1/2 starts with a risk check and genetic counseling. Whether a medicine makes sense after that is a decision with your doctor or genetic counselor. Read more: BRCA risk assessment.
Is the recommendation being updated?
An update is in progress. On our review the USPSTF update page was last updated March 14, 2024 and showed no draft recommendation yet, so the 2019 statement still applies. (USPSTF, 2019)
This page explains what the guidelines say. It cannot tell you what is right for you: talk to your doctor.