Using low dose tamoxifen with or without omega-3 fatty acids to reduce breast cancer risk

Phase 2 Study of Low Dose Tamoxifen +/- High Dose Omega-3 Fatty Acids in Overweight Postmenopausal Women at Increased Risk for Breast Cancer

Phase 2 Interventional National Cancer Institute (NCI) · NCT06195306

This study is testing whether adding omega-3 fatty acids to low dose tamoxifen can help reduce the risk of breast cancer in overweight or obese postmenopausal women.

Quick facts

PhasePhase 2
Study typeInterventional
Enrollment66 (estimated)
Ages45 Years to 74 Years
SexFemale
SponsorNational Cancer Institute (NCI) NIH
Drugs / interventionsradiation
Locations3 sites (Kansas City, Kansas and 2 other locations)
Trial IDNCT06195306 on ClinicalTrials.gov

What this trial studies

This phase II trial evaluates the effectiveness of low dose tamoxifen, with or without the addition of omega-3 fatty acids, in reducing the risk of breast cancer among postmenopausal women who are overweight or obese. The study aims to measure changes in serum adiponectin levels and assess the impact on insulin resistance and estrogen response in benign breast tissue. Participants will be randomized to receive either tamoxifen alone or tamoxifen combined with omega-3 fatty acids for a duration of six months. The trial includes various assessments, including blood tests and mammography, to monitor the effects of the interventions.

Who should consider this trial

Good fit: Ideal candidates for this study are postmenopausal women aged 45 to 65 who are overweight or obese and at increased risk for breast cancer.

Not a fit: Patients who are not postmenopausal or those with a normal body mass index may not receive any benefit from this study.

Why it matters

Potential benefit: If successful, this approach could significantly lower the risk of breast cancer in high-risk postmenopausal women.

How similar studies have performed: Other studies have shown promise in using tamoxifen for breast cancer prevention, but the combination with omega-3 fatty acids is a novel approach.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Age 45 - 74
* Postmenopausal female

  * Postmenopausal is defined as either

    * Prior removal of the ovaries, or if ovaries intact amenorrhea for \>= 12 months and not on any form of contraception, or
    * Amenorrhea for greater than 2 months with serum follicle-stimulating hormone (FSH) in postmenopausal range (\>= 25 IU/L). Women with ovaries and a prior hysterectomy or endometrial ablation \< age 55 must have a FSH \>= 25 IU/L. Women may be on vaginal low dose estrogen preparations for vaginal dryness. Women over age 50 with a levonorgestrel intrauterine device in place for 2 or more years and not planning removal in the next 6 month are also eligible if FSH \>= 25 IU/L

      * Note: FSH will be done at time of screening
* Women with intact ovaries and uterus \< age 55 must have a negative pregnancy test prior to randomization
* Overweight or obese (body mass index \[BMI\] \>= 25 kg/m\^2)

  * Note: BMI must be calculated within 28 days of randomization
* Willing to undergo a fasting blood draw and non-fasting RPFNA with fixed and frozen aliquots sent to University of Kansas Medical Center (KUMC)
* At increased risk of breast cancer per at least one of the following:

  * Personal medical history

    * History of atypical hyperplasia or lobular carcinoma in situ (LCIS) found on breast biopsy
    * History of unilateral ductal carcinoma in situ treated with unilateral mastectomy, lumpectomy, or local excision with or without radiation and this treatment was completed at least 3 months prior to the screening RPFNA
    * High mammographic density determined by one of the following:

      * Visual estimate of area of density (VAS) \> 50%,
      * Volpara (trademark) \>= 15% dense volume (Volpara d)
      * Breast Imaging Reporting and Data System (BIRADS) assessment = extremely dense (BIRADs D)
  * Genetic test result

    * Germline gene mutation in ATM, BARD1, BRCA2, CDH1, CHEK2, NF1, PALB2, PTEN, RAD51C, RAD51D, or STK11
    * Polygenic lifetime risk score \>= 2x average or 25%
  * Calculated risk based on standard models

    * Five-year Breast Cancer Risk Assessment Tool (BCRAT) (version 2.0) \>= 1.66%
    * Ten-year International Breast Cancer Intervention Study risk evaluation tool (IBIS) (version 8) \>= 3%
    * Ten-year relative risk IBIS (version 8) \>= 2X that for age group
    * Ten- year Breast Cancer Surveillance Consortium (version 2) \>= 3%
  * Family History

    * Breast cancer in a first or second degree relative (female or male) with onset under age 50. (First degree relative = parent, sibling, or child. Second degree relative = grandparent, uncle, aunt, nephew, niece, half-sibling, grandchild or first cousin)
    * Breast cancer in two or more first or second-degree relatives from either the maternal or paternal linage without regard to age
    * Bilateral breast cancer or breast and ovarian cancer in the same first or second degree relative without regard to age
  * Primary source documentation of risk is required and must be submitted to the lead academic organization (LAO) for review along with the eligibility checklist

    * Risk factor: Atypical hyperplasia or LCIS; Primary source document: Copy of pathology report or clinical note confirming the diagnosis
    * Risk factor: Ductal carcinoma in situ (DCIS) and treatment history; Primary source document: Copies of pathology report or clinic notes confirming the diagnosis, treatment plan and treatment end date(s)
    * Risk factor: Mammographic density; Primary source document: Copy of clinic note or mammogram report
    * Risk factor: Genetic; Primary source document: Copy of genetic test report
    * Risk factor: Calculated based on standard models; Primary source document: Copy of the calculation result
* Total bilirubin =\< 1.5 x institutional upper limit of normal (ULN)

  * Note: Higher total bilirubin levels (=\< 3 mg/dL) can be allowed if due to known benign liver condition, i.e., Gilbert's syndrome
  * Results from prior laboratory testing within 180 days of randomization may be used
* Aspartate aminotransferase (AST) (serum glutamic-oxaloacetic transaminase \[SGOT\]) =\< 3.0 x institutional upper limit of normal

  * Results from prior laboratory testing within 180 days of randomization may be used
* Alanine aminotransferase (ALT) (serum glutamate pyruvate transaminase \[SGPT\]) =\< 3.0 x institutional upper limit of normal

  * Results from prior laboratory testing within 180 days of randomization may be used
* Human immunodeficiency virus (HIV)-infected patients on effective anti-retroviral therapy with undetectable viral load within 6 months are eligible for this trial
* For patients with evidence of chronic hepatitis B virus (HBV) infection, the HBV viral load must be undetectable on suppressive therapy, if indicated
* Patients with a history of hepatitis C virus (HCV) infection must have been treated and cured. For patients with HCV infection who are currently on treatment, they are eligible if they have an undetectable HCV viral load
* Patients on chronic suppressive antiviral therapy for herpes simplex virus (HSV) are eligible
* Eastern Cooperative Oncology Group (ECOG) performance status =\< 2 (Karnofsky \>= 60%)
* Women must have at least 1 unaffected untreated breast for fine needle aspiration. Women may have had prior unilateral breast radiation or mastectomy for DCIS
* Ability to understand and the willingness to sign a written informed consent document
* Most recent screening mammogram must be performed ≤ 12 months prior to RPFNA and must be reported as BIRAD 1 or 2. If BIRAD 0 then follow-up diagnostic imaging must be BIRAD 1 or 2 or cleared clinically with radiology recommendation of return to annual screening
* Confirmation that baseline research blood was drawn fasting (\>= 10 hours), has been received in good condition at KUMC, and is archived for assessment of primary endpoint

Exclusion Criteria:

* Exclusions based on current or past conditions:

  * Bilateral breast implants (danger of implant puncture with RPFNA)
  * Prior invasive breast cancer
  * Prior invasive uterine cancer
  * Other prior invasive cancer and haven't completed cancer related therapy or with evidence of disease (other than non-melanoma skin cancer) within the past 2 years
  * Currently breastfeeding (concern that tamoxifen may be in breast milk) or nursing within past 12 months (concern about milk fistula with RPFNA)
  * Type I or type II diabetes mellitus requiring current pharmacologic treatment (including metformin, glucagon-like peptide 1 agonists, insulin, sulfonylurea)
  * Prior deep vein thrombosis, pulmonary embolus, or stroke
  * Prior gastric bypass surgery
  * History of chronic liver disease including NASH (nonalcoholic steatohepatitis) or cirrhosis
  * Pathogenic or likely pathogenic germline mutation in BRCA1 or TP53
* Exclusions based on medications:

  * Current use of prescription anticoagulants such as Coumadin (warfarin), direct-acting oral anticoagulants such as Xarelto (rivaroxaban) or Eliquis (apixaban) or heparin
  * Women who would not be able to or do not wish to discontinue daily use of aspirin (81mg or higher) and aspirin containing products (81 mg or higher) at least 3 weeks prior to each RPFNA

    * Note: Women may resume daily use of aspirin and aspirin containing products 3 days after each RPFNA procedure
  * Current use of a levonorgestrel intrauterine device if in place less than 2 years or if there is planned removal within the next 6 months
  * Current use of hormone therapy (oral, transdermal, or injectable)

    * Note: Vaginal estrogen is allowed
  * Prior treatment with tamoxifen, aromatase inhibitor or selective estrogen receptor degrader for more than 2 months

    * Note: Women with \< 2 months of these drugs must be off for at least 6 months before they may begin biomarker screening tests
  * Greater than 1 gram daily of omega-3 fatty acid supplement within the last 6 months
  * Current use of prescription immunosuppressive drugs
  * Current use of CYP3A4 strong inducers rifampin or aminoglutethimide
  * Current use of or plans to initiate a glucagon-like peptide 1 agonist within the next 6 months
  * Current use of metformin for any indication
* Participants may not be receiving any other investigational agents
* History of allergic reactions attributed to compounds of similar chemical or biologic composition to tamoxifen or omega-3 fatty acid or generic Lovaza or compounds of similar chemical composition
* Uncontrolled intercurrent illness or psychiatric illness/social situations that would limit compliance with study requirements

Where this trial is running

Kansas City, Kansas and 2 other locations

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Breast Atypical HyperplasiaBreast CarcinomaBreast Ductal Carcinoma In SituBreast Lobular Carcinoma In Situ
Last reviewed 2026-06-13 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.