Clinical trial Recruiting at 9 sites Phase 2 Interventional Ages 18 and up Men only

Treatment for male breast cancer using endocrine therapy

Official title: ETHAN: A Phase II Study Comparing Different Endocrine THerapies for mAle Breast caNcer

Run by Dana-Farber Cancer Institute · NCT05501704 · Data updated 2026-11-12

This study is testing different combinations of hormone therapy for men with early to mid-stage breast cancer to see which one works best compared to the usual treatment.

Quick facts

PhasePhase 2
Study typeInterventional
Ages18 Years and up
SexMen only
Enrollment60 (estimated)
SponsorDana-Farber Cancer Institute
Academic / other
Drugs / interventionschemotherapy, radiation
Locations9 sites (Washington D.C., District of Columbia and 8 other locations)
StatusRecruiting
StartedOctober 11, 2023
Main results expectedApril 1, 2027
Study endsApril 1, 2036
Registry record updatedAugust 24, 2026
Trial IDNCT05501704 on ClinicalTrials.gov

Is this trial a fit for you?

Likely a good fit

Ideal candidates are men aged 18 years or older with a diagnosis of invasive hormone receptor-positive, HER2-negative breast cancer who have not yet undergone surgery.

Probably not a fit

Patients with breast cancer that is not hormone receptor-positive or HER2-positive, or those who have already had surgical resection, may not benefit from this study.

A plain-English reading of the study's rules. Only the study team can confirm whether you qualify.

What this trial studies

This clinical trial investigates the effectiveness of various endocrine therapy regimens for men with stage I-III hormone receptor-positive breast cancer. Participants will undergo a 3-week window phase of treatment followed by a 4-month treatment phase, where they will receive one of four combinations of endocrine therapies, including Tamoxifen, Anastrozole, Degarelix, and Abemaciclib. The study aims to determine how well these treatments work in comparison to the standard care. Participants will be monitored for up to 10 years after treatment completion to assess long-term outcomes.

Why it matters

Potential benefit: If successful, this study could provide more effective treatment options for men with breast cancer, potentially improving survival rates and quality of life.

How similar studies have gone: Other studies have shown promise with endocrine therapies in breast cancer treatment, but this specific approach for male breast cancer is relatively novel.

Who can join: the full rules

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Men aged 18 years or older, with diagnosis of invasive breast cancer who have not undergone surgical resection of the primary tumor and axillary nodes.
* Stage I, II, or III per American Joint Committee on Cancer (AJCC) staging 8th edition (112).
* Breast cancer must be hormone receptor-positive and HER2-negative according to definition below assessed by local pathology.

  * Hormone receptor-positive is defined as: positivity for at least one of the hormone receptors (estrogen receptor \[ER\] or progesterone receptor \[PR\]) by IHC. ER and PR assays are considered positive if there are \> 1% positive tumor nuclei in the samples.
  * HER2-negative is defined per the current American Society of Clinical Oncology/College of American Pathologists Clinical Practice Guideline (113).
* Patients with multifocal or multicentric disease are eligible if the treating investigator has determined the patient should be treated as ER-positive and HER2-negative.
* Bilateral breast cancers are allowed if the treating investigator has determined the patient should be treated as ER-positive and HER2-negative.
* Patients with a history of ipsilateral or contralateral DCIS or LCIS are eligible.
* ECOG performance status ≤ 2.
* Required laboratory values demonstrating adequate organ function:

  * ANC ≥ 1000/mm3
  * Hemoglobin ≥ 8 g/dl
  * Platelets ≥ 50,000/mm3
  * Serum creatinine ≤ 3.0 x ULN (institutional)
  * Total bilirubin ≤ 2.0 x ULN (institutional).
  * AST and ALT ≤ 5.0 x ULN (institutional)
* Men with partners of childbearing potential must be willing to use one highly effective form of non-hormonal contraception or two effective forms of non-hormonal contraception by the patient and/or partner and continue its use for the duration of the study treatment and for 6 months after the last dose of study treatment.
* Non-English-speaking patients are eligible but will be exempt from patient-completed questionnaires.
* Willing and able to sign informed consent.
* Willing to undergo breast biopsy after completion of window phase.
* Patient is able to swallow oral medications.

Exclusion Criteria:

* Prior endocrine therapy, chemotherapy, radiation therapy, or investigational therapy for the current breast cancer diagnosis.
* Prior endocrine therapy, systemic therapy, radiation therapy, or investigational therapy for any other malignancy within the past 12 months.
* Diagnosis of inflammatory breast cancer (T4d).
* Other concurrent serious diseases that may interfere with planned treatment, including severe cardiac disease, congestive heart failure (CHF) of New York Heart Association (NYHA) Class III or higher, severe pulmonary conditions/illness, uncontrolled infections.
* The patient has serious and/or uncontrolled preexisting medical condition(s) that, in the judgment of the investigator, would preclude participation in this study (for example, interstitial lung disease, severe dyspnea at rest or requiring oxygen therapy, severe renal impairment \[e.g. estimated creatinine clearance \<30ml/min\], history of major surgical resection involving the stomach or small bowel, or preexisting Crohn's disease or ulcerative colitis or a preexisting chronic condition resulting in baseline Grade 2 or higher diarrhea).
* The patient has active systemic bacterial infection (requiring intravenous \[IV\] antibiotics at time of initiating study treatment), fungal infection, or detectable viral infection (such as known human immunodeficiency virus positivity or with known active hepatitis B or C \[for example, hepatitis B surface antigen positive\]. Screening is not required for enrollment.
* The patient has a personal history of any of the following conditions: syncope of cardiovascular etiology, ventricular arrhythmia of pathological origin (including, but not limited to, ventricular tachycardia and ventricular fibrillation), or sudden cardiac arrest.

Where it's running

  • Georgetown University Medical Center
    Washington D.C., District of Columbia, United States
    Recruiting
  • Mayo Clinical Hospital Florida
    Jacksonville, Florida, United States
    Recruiting
  • Dana Farber Cancer Institute
    Boston, Massachusetts, United States
    Recruiting
  • Mayo Clinic
    Rochester, Minnesota, United States
    Recruiting
  • UNC Lineberger Comprehensive Cancer Center
    Chapel Hill, North Carolina, United States
    Recruiting
  • University of Pennsylvania, Abramson Cancer Center
    Philadelphia, Pennsylvania, United States
    Recruiting
Show 3 more locations
  • University of Pittsburgh Cancer Institute
    Pittsburgh, Pennsylvania, United States
    Recruiting
  • Vanderbilt Cancer Center
    Nashville, Tennessee, United States
    Recruiting
  • M. D. Anderson Cancer Center at University of Texas
    Houston, Texas, United States
    Recruiting

Study contacts

Similar studies

Other studies for the same condition or treatment. Recruiting studies are listed first.

How to take part

  1. Review the eligibility criteria above with your treating physician.
  2. Check the official listing on ClinicalTrials.gov for the latest contact details and recruitment status.
  3. Contact the study coordinator or principal investigator to ask for pre-screening. Pre-screening is free and never obligates you to enroll.
Last reviewed 2026-11-14 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.