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Phase II Study of Low-Dose Exemestane vs. Tamoxifen for Breast Cancer Risk

This study is looking at two low-dose medications, exemestane and tamoxifen, to see how well they work and how safe they are for post-menopausal women who have a high risk of developing breast cancer. Both exemestane (a steroidal aromatase inhibitor) and tamoxifen (a selective estrogen receptor modulator) are already used to treat breast cancer or reduce risk at full doses. This trial aims to see if lower doses are effective with fewer side effects. The main goal is to see if there's a difference in how these medications affect your quality of life related to menopause symptoms after 12 months. You may be eligible if you are a post-menopausal woman. The study is currently unclear on its recruitment status and plans to enroll about 140 women.

Study design
This is a randomized, double-blind, Phase II study involving about 140 participants. You would be randomly assigned to receive either exemestane or tamoxifen, and neither you nor your doctor would know which medication you are receiving.
What's involved
If you join, you will have screening for eligibility, in-clinic visits, questionnaires, blood tests, mammograms, and bone density (DEXA) scans. Your participation is expected to last about 12 months.
Compensation
Not stated in the trial record.
Follow-up
The primary endpoint is measured at 12 months, which suggests follow-up for at least that duration.

AI-generated from the public study record. Only the study team can confirm whether you're eligible — confirm details with them before making decisions.

NCT07499999

Randomized Double-Blind Phase II Trial of Baby Exemestane Versus Baby Tamoxifen in Post-Menopausal Women at High Risk for Breast Cancer

Not Yet Recruiting
PHASE2All AgesInterventionalPrevention
Dana-Farber Cancer Institute
~140 participants
Updated 2026-03-30 on ClinicalTrials.gov
What's tested:ExemestaneTamoxifen

At a glance

Recruiting sites
0 of 2 listed sites are recruiting right now
RecruitingSuspended, closed, or not yet open
What they're measuring
Difference in Overall Domain Score Change From Baseline in Menopause-Specific Quality of Life Questionnaire (MENQOL) Between the Two Arms at 12 Months
Measured over 12 Months

Conditions

Breast Cancer
Ductal Carcinoma
Estrogen-receptor-positive Breast Cancer
Atypical Lobular Hyperplasia
BRCA2 Mutation
CHEK2 Gene Mutation
Ataxia Telangiectasia Mutated Gene Mutation

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Where it's being run

2 sites across 1 states
Massachusetts2

Study leadership

  • Judy Garber, MD. MPH · PRINCIPAL_INVESTIGATOR · Dana-Farber Cancer Institute

Who to contact

Judy Garber, MD, MPH
[email protected]
617-632-2282
Email the study team

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Do you actually qualify for this trial?

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Eligibility criteria

Inclusion

Postmenopausal state is defined⁸ as no menses for 12 months without an alternative medical cause. A high follicle stimulating hormone (FSH) level in the postmenopausal range may be used to confirm a post-menopausal state in women not using hormonal contraception or hormonal replacement therapy.
Any of the following criteria must be met:
Recent (within 12 months from date of consent form signature) histologic diagnosis of ER+ve (\>5%) DCIS (patients with DCIS should have undergone breast-conserving therapy i.e. lumpectomy to remove the tumor with negative surgical margins followed by radiotherapy (see footnote 1 below)) diagnosis within 3 years of HRL (ADH, LCIS, ALH), or;
At least 3% breast cancer risk at 5 years (or 5% risk at 10yrs) per one of the following risk models: the Breast Cancer Surveillance Consortium risk calculator V3 or Tyrer-Cuzick model V8 or;
Known carriers of a germline pathogenic/likely pathogenetic variant in the following moderate penetrance genes (CHEK2 or ATM), or women with chest wall irradiation before age of 30 years
Eastern Cooperative Oncology Group - Performance Status (ECOG-PS) 0-1
Able to swallow oral medications
Participants with a prior or concurrent malignancy whose natural history or treatment does not have the potential to interfere with the safety or efficacy assessment of the investigational regimen are eligible for this trial. Specifically, all cancers diagnosed since 3 years or longer except for breast and endometrial are eligible.
Ability to understand and the willingness to sign a written informed consent document
Mammography performed up to 6 months before the trial consent form signature
DEXA performed up to 12 months before the trial consent form signature
Life expectancy ≥ 10 years
Normal liver function tests and blood cell count
Negative gynecological examination performed up to 6 months before the trial consent form signature.

Exclusion

Pre/perimenopausal women: exemestane is only effective in post-menopausal women
History of DVT or PE: tamoxifen can increase tendency to blood clot
Endometrial cancer: full-dose tamoxifen is associated with increased risk of endometrial cancers
Macular disorders: tamoxifen is associated with retinal damage
Inability to comply with study procedures: standard
Prior use of antiestrogens within 12 months from the date of the trial consent form signature: there can be long duration effects from antiestrogens that could influence trial drug effects
Use of hormone replacement therapy (HRT) within 3 months from the date of the trial consent form signature: similarly, wish to avoid any long lasting effect before alternate effect from study drugs
Severe osteoporosis (T score ≤ 2.5 at either spine or hip), or recent vertebral fracture (within 6 months) not treated with zoledronic acid or denosumab: Exemestane is an aromatase inhibitor which can worsen bone loss (osteoporosis)
Current use of terbinafine, quinidine, cinacalcet, rifampicin, phenytoin, carbamazepine, phenobarbital, St. John's wort, warfarin, erythromycin, cyclosporin, nifedipine and any concomitant coumarin-type anti-coagulant therapy: these drugs compete for the Cytochrome P450 metabolic pathways of tamoxifen and exemestane
Moderate or severe renal impairment: Exemestane is eliminated equally by liver and renal metabolism
Known hypersensitivity to study drugs: standard
Postmenopausal status, and any of the following:
Histological report of ER-positive DCIS within 12 months, or HRL of the breast within 3 years from date of consent form signature, or;
Report of risk assessment ≥3% in 5 years or 5% in 10 years of breast cancer according to the selected risk model(s) different criteria within 6 months from screening, or;
Documentation of women carriers of a germline pathogenic/likely pathogenetic variant in a moderate penetrance gene (CHEK2 or ATM), or;
Documented history of chest wall radiotherapy before age 30.
Inclusion of Women and Minorities

What this trial measures

  • Difference in Overall Domain Score Change From Baseline in Menopause-Specific Quality of Life Questionnaire (MENQOL) Between the Two Arms at 12 Months12 Months

    The MENQOL assesses the degree to which menopausal symptoms are troublesome in four domains: vasomotor (three items), sexual (three items), physical (seven items), and psychosocial (16 items). Each item is answered with Yes or No. If the response is Yes, the participant rates how bothersome the symptom was on a scale from 0 to 6, where 0 indicates "not at all bothered" and 6 indicates "extremely bothered." For each participant, the difference between the baseline and 12-month overall MENQOL score will be calculated and defined as the "change."