Acolbifene Versus Low Dose Tamoxifen for the Prevention of Breast Cancer in Premenopausal Women at High Risk for Development of Breast Cancer
Eligible age
35+ yrs
Accepts
Women
Locations
4 states
Healthy volunteers
No
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About this study
This phase IIA trial compares the effect of acolbifene versus low dose tamoxifen in preventing breast cancer in premenopausal women at high risk for developing breast cancer. The usual approach for patients at increased risk for breast cancer is to undergo yearly breast magnetic resonance imaging or ultrasound in addition to yearly mammogram. Premenopausal women at very high lifetime risk for breast cancer (greater than 50%) can consider preventive removal (mastectomy) of both breasts. Premenopausal women age 35 or older with a prior diagnosis of atypical hyperplasia, lobular carcinoma in situ, or an estimated 10-year risk of greater than or equal to 3% or estimated 10-year risk of greater than or equal to 2-5 times that of the average woman (depending on age) may be advised to consider five years of standard dose tamoxifen. Standard dose tamoxifen is four times the dose used in this study. Estrogen can cause the development and growth of breast cancer cells. Acolbifene and tamoxifen blocks the use of estrogen by breast cells. This study may help researchers measure the effects of acolbifene and low dose tamoxifen on markers of breast cancer risk in mammogram imaging, breast tissue, and in blood samples.
Sponsor: National Cancer Institute (NCI)
You may qualify if…
- ✓ Age \>= 35 years
- ✓ Considered clinically premenopausal
- ✓ Having regular menstrual cycles (between 21 and 35 days) unless a contraceptive device such as progestin containing intrauterine device (IUD) (e.g., Mirena IUD) is being used which suppresses menstrual periods, or premenopausal women who have undergone a hysterectomy, but ovaries are intact
- ✓ Not considering pregnancy for at least 12 months
- ✓ Women of child-bearing potential capacity must be willing to have used effective birth control precautions for 8 weeks prior to fine needle aspiration and be willing to continue for 8 weeks after study completion as tamoxifen may have teratogenic effects on the developing fetus. Reproductive and developmental toxicity studies have not been conducted with acolbifene. Should a woman become pregnant or suspect she is pregnant while participating in this study, she must stop study drug and inform her study physician immediately.
- ✓ For women not using oral contraceptive (progestin alone or estrogen plus a progestin), two of the following are recommended but woman must agree to at least one of the following methods:
- ✓ IUD non-hormonal or hormone containing (usually a progestin) intrauterine device (IUD) or rings. Any of these should have been inserted at least 8 weeks prior to RPFNA.
- ✓ Barrier method (such as condoms and diaphragms or cervical caps with or without a spermicide)
You may not qualify if…
- ✕ Bilateral breast implants (danger of implant puncture with RPFNA)
- ✕ Women who are pregnant
- ✕ Currently breastfeeding (concern that tamoxifen or acolbifene may be in breast milk) or nursing within the past 12 months (concern about milk fistula with RPFNA)
- ✕ Prior invasive breast cancer within the past 5 years
- ✕ Other prior invasive cancer \> T1 stage (other than non-melanoma skin) within the past 5 years
- ✕ Pathogenic or likely pathogenic germline mutation in BRCA1/2 or PALB2 (These latter individuals are likely to undergo yearly ovarian screening and enlarging cysts could raise concern about ovarian cancer and lead to unnecessary diagnostic procedures)
- ✕ Type I or Type II diabetes mellitus requiring treatment with prescription medication
- ✕ Prior deep vein thrombosis, pulmonary embolus, or stroke
Where it's recruiting
Source: ClinicalTrials.gov · NCT05941520 · last updated 2026-05-13