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Low-Dose Tamoxifen Citrate in Reducing Breast Cancer Risk in Radiation-Induced Cancer Survivors

Low-Dose Tamoxifen for Radiation-Induced Breast Cancer Risk Reduction: A Phase IIB Randomized Placebo-Controlled Trial

Status
Active, not recruiting
Phases
Phase 2
Study type
Interventional
Source
ClinicalTrials.gov
Registry ID
NCT01196936
Acronym
LDTam
Enrollment
84
Registered
2010-09-09
Start date
2010-09-30
Completion date
2028-12-11
Last updated
2026-01-05

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Breast Cancer

Keywords

Cancer survivors, Low Dose Tamoxifen, Breast Cancer Risk Reduction

Brief summary

Estrogen can cause the growth of breast cancer cells. Hormone therapy using tamoxifen citrate may fight breast cancer by blocking the use of estrogen by the tumor cells This phase IIb trial studies how well low-dose tamoxifen citrate works in reducing breast cancer risk in radiation-induced cancer survivors.

Detailed description

PRIMARY OBJECTIVES: I. To determine the impact of a two-year course of low-dose tamoxifen (tamoxifen citrate) administered at 5 mg per day on surrogate endpoint biomarkers of breast cancer (BC) risk, including: mammographic breast density (MBD), an established radiographic biomarker of BC risk; cytomorphology and proliferative index, tissue biomarkers closely linked to BC risk; and sex steroid hormones and insulin growth factors, circulating biomarkers of BC risk. II. To establish safety and tolerability of this low-dose tamoxifen regimen, assessing both objective measures (lipid profiles, clotting factors and bone metabolism markers) and patient-reported outcomes. III. To examine the modifying effect of demographic, clinical, and molecular characteristics on the risk: benefit ratio from this two-year low dose tamoxifen intervention. IV. To explore the relationship between this low-dose tamoxifen regimen and clinical measures of efficacy (new breast cancer and ductal carcinoma in situ \[DCIS\] diagnoses) and toxicity (thromboembolic events, reports of hot flashes and gynecological symptoms, liver function abnormalities, and other cancer diagnoses). OUTLINE: Patients are randomized to 1 of 2 treatment arms. ARM I: Patients receive tamoxifen citrate orally (PO) once daily for 24 months in the absence of disease progression or unacceptable toxicity. ARM II: Patients receive placebo PO once daily for 24 months in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up periodically for up to 10 years.

Interventions

DRUGTamoxifen Citrate

5 mg PO Daily

DRUGPlacebo

1 tablet daily

Correlative studies

OTHERimmunohistochemistry staining method

Correlative Studies

OTHERpharmacological study

Correlative Studies

OTHERlaboratory biomarker analysis

Correlative Studies

GENETICprotein expression analysis

correlative studies

OTHERpharmacogenomic studies

correlative studies

OTHERquestionnaire administration

Ancillary studies

OTHERQuality of Life Assessment

Ancillary Studies

Sponsors

National Cancer Institute (NCI)
CollaboratorNIH
St. Jude Children's Research Hospital
CollaboratorOTHER
University Health Network, Toronto
CollaboratorOTHER
University of Michigan
CollaboratorOTHER
Dana-Farber Cancer Institute
CollaboratorOTHER
Mayo Clinic
CollaboratorOTHER
University of Washington
CollaboratorOTHER
City of Hope National Medical Center
CollaboratorOTHER
M.D. Anderson Cancer Center
CollaboratorOTHER
University of Chicago
CollaboratorOTHER
University of Minnesota
CollaboratorOTHER
University of Colorado, Denver
CollaboratorOTHER
Wake Forest University
CollaboratorOTHER
University of Alabama at Birmingham
Lead SponsorOTHER

Study design

Allocation
RANDOMIZED
Intervention model
PARALLEL
Primary purpose
PREVENTION
Masking
TRIPLE (Subject, Investigator, Outcomes Assessor)

Eligibility

Sex/Gender
FEMALE
Age
25 Years to No maximum
Healthy volunteers
No

Inclusion criteria

* Exposure to radiation therapy (RT) delivered to the chest, axilla, and/or supraclavicular areas at a cumulative dose of 12 Gy or more by age 40 years; in addition, patients who received total body irradiation by age 40 may be considered * No evidence of active disease from their primary cancer for at least 2 continuous years prior to registration; the indication for RT is not specified but cannot be for primary breast cancer; common examples include, but are not limited to: lymphoma, leukemia, sarcoma, and Wilms tumor occurring in pediatric patients, and lymphoma, leukemia, and sarcoma occurring in young adults; primary cancer therapy must have been completed at least 6 months prior to registration * Well-defined menopausal status falling into one of the following categories: * Premenopausal, defined as age at registration 45 years old or younger with regular monthly period for at least 6 consecutive months prior to registration * Postmenopausal, defined as continuous absence of menstruation for 12 months OR status-post bilateral oophorectomy OR follicle stimulating hormone (FSH) level in the postmenopausal range

Exclusion criteria

* Subsequent malignant neoplasm (SMN) other than those listed below diagnosed within 2 years of study entry; patients with the listed indolent or pre-invasive neoplasms may be eligible if diagnosed within 2 years and all treatment was completed at least 6 months prior to registration: * Non-melanoma cancers of the skin * Thyroid cancer * Cervical cancer confined to the cervix or cervical intraepithelial neoplasia (CIN) * Ductal carcinoma in situ (DCIS) or breast intraepithelial neoplasia (IEN) (includes atypical hyperplasia and lobular carcinoma in situ \[LCIS\]), or * Superficial or non-invasive transitional cell carcinoma of the bladder * For women with a prior history of DCIS or breast IEN, only one breast could have been involved and all therapy must have been completed at least 6 months prior to registration; in addition women with a prior history of invasive breast cancer may also be eligible, as long as only one breast was involved, they were diagnosed at least 2 years prior to study entry, and therapy was completed at least 6 months prior to study entry * Bilateral breast implants or status-post bilateral prophylactic mastectomy * Evidence of malignant breast disease on any form of breast imaging; the study only requires annual mammography; however, annual breast magnetic resonance imaging (MRI) is considered standard of care in this patient population (per Children's Oncology Group \[COG\] or National Comprehensive Cancer Network \[NCCN\] follow-up guidelines), and breast ultrasound may be indicated if a palpable lesion is detected on screening clinical breast exam; abnormal imaging may require additional radiographs and/or breast biopsy; patients who are found to have benign breast disease with or without atypia may continue on study as long as there is no evidence of malignancy; if there is evidence of malignancy, and only one breast is involved, they may be reapproached 6 months after completion of therapy for consideration of the trial * Baseline categorical mammographic density scored as BIRAD 1, or extremely fatty, in both breasts; if the patient has a prior history of IEN (DCIS, LCIS, or atypical hyperplasia), the contralateral breast must not have a mammographic density score of BIRAD 1; this determination will be made at the local site * Current or recent use (within 6 months of registration or baseline mammogram, whichever is first) of any of the following: systemic hormone replacement therapy (includes oral or transdermal formulations); Vagifem and Estring, two formulations of locally applied vaginal estrogen associated with minimal systemic absorption, may be allowed; other estrogen-containing vaginal creams, while not an exclusion, should be avoided whenever possible; patients with a history of hormone modifying herbal supplements are eligible, but patients will be asked to avoid their use after on study * Current or recent use (within 6 months of registration or baseline mammogram, whichever is first) of any of the following: hormonal forms of contraception (includes oral, transdermal, implanted, and injectable formulations): selective estrogen receptor modifiers; aromatase inhibitors; GnRH analogs; androgens or antiandrogens * Concurrent use of warfarin and strong inhibitors or CYP2D6 will not be allowed * A personal history or a strong family of thromboembolism, including deep venous thrombosis (DVT), pulmonary embolus (PE), or cerebrovascular accident (CVA); a personal history of transient ischemic attack (TIA) or retinal vein thrombosis will also not be allowed; in addition, patients with a condition known to increase hypercoagulability, such as Factor V Leiden disease, will be excluded; patients with atrial fibrillation will be excluded, due to risk of CVA, but patients with coronary artery disease or congestive heart failure without atrial fibrillation will be allowed to participate * Current intrauterine pregnancy or plans to become pregnant within two years; in addition, currently nursing mothers will be excluded * Serum creatinine \> 2X the institutional norm * Total bilirubin \> 2X the institutional norm * Serum glutamic oxaloacetic transaminase (SGOT) or serum glutamic pyruvic transaminase (SGPT) \> 2X the institutional norm * Unable to provide consent

Design outcomes

Primary

MeasureTime frameDescription
Mammographic Breast DensityAt year two post treatmentMammographic density was quantified as percentage of fibroglandular tissue. Using an intention-to-treat analysis, mammographic breast density (MBD) was compared between patients in the low dose tamoxifen intervention and placebo group by applying the linear mixed effects model for normally distributed data.

Secondary

MeasureTime frameDescription
Number of Grade 2-4 ToxicitiesUp to 2 yearsWill be tabulated by treatment arm. Differences by treatment arm will be evaluated using Fisher exact tests.
Biomarker LevelsUp to 2 yearsTotal cholesterol, low and high density lipoprotein, triglycerides, and anti-thrombin III enzymatic assay measurements will be treated as continuous variables. Transformed to normality as appropriate, the linear mixed effects model will be applied, using the unstructured mean model and linear in time model to assess the effects of low-dose tamoxifen on these measurements over time.
Percentage of Pills Taken Out of the Total PrescribedUp to 2 yearsThe number of pills taken out of the total prescribed in a 3-month period will be modeled as a random effects binomial regression model. The binomial rates from 8 time points (month 3-24) will be modeled as unstructured mean model with 7 indicator variables as well as polynomial models over time. The random-intercept and the random intercept and slope models will be considered. The significance of the time indicators or parameters by treatment interaction will be evaluated for treatment difference in compliance.
Insulin Growth Factor Levels (IGF1)Up to 2 yearsIGF1 will be treated as a continuous measure. The linear mixed effects model for between group comparisons of measures from 3 time points will be applied. The unstructured mean model and linear in time model will be employed.
Insulin Growth Factor Levels (IGF3 )Up to 2 yearsIGF3 will be treated as a continuous measure. The linear mixed effects model for between group comparisons of measures from 3 time points will be applied. The unstructured mean model and linear in time model will be employed.
Biomarker Levels - Alkaline PhosphataseUp to 2 yearsSerum bone-specific alkaline phosphatase measurements will be treated as continuous variables. Transformed to normality as appropriate, the linear mixed effects model will be applied, using the unstructured mean model and linear in time model to assess the effects of low-dose tamoxifen on these measurements over time.
Biomarker Levels - Urine N-telopeptideUp to 2 yearsUrine n-telopeptide measurements will be treated as continuous variables. Transformed to normality as appropriate, the linear mixed effects model will be applied, using the unstructured mean model and linear in time model to assess the effects of low-dose tamoxifen on these measurements over time.
Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireUp to 2 yearsThe outcomes will be scored as a 5-point Likert-type scale (0-4) in response to questions on how much the patients are bothered by certain symptoms. The questionnaire will be administered every 6 months. The responses will be treated as normally distributed, as ordinal or dichotomized variable, and the linear mixed effects of general linear mixed model (GLMM) methods will be applied to compare changes between treatment groups. Piecewise models will also be fitted with join point at 6 months, considering linear and curvilinear trajectories between 6 and 24 month time points.

Countries

Canada, United States

Participant flow

Recruitment details

Participants were screened for eligibility at each participating institution.However, after central review of mammograms, 11 participants were ineligible for the study (mammographic density \<25%) and 1 participant was randomized but withdrew before taking the study drug. These 12 participants were excluded from the analysis.

Participants by arm

ArmCount
Arm I (Tamoxifen Citrate)
Patients receive tamoxifen citrate PO QD for 24 months in the absence of disease progression or unacceptable toxicity. Tamoxifen Citrate: 5 mg PO Daily Digital mammography: Correlative studies immunohistochemistry staining method: Correlative Studies pharmacological study: Correlative Studies laboratory biomarker analysis: Correlative Studies protein expression analysis: correlative studies pharmacogenomic studies: correlative studies questionnaire administration: Ancillary studies Fine needle aspiration Quality of Life Assessment: Ancillary Studies
34
Arm II (Placebo)
Patients receive placebo PO QD for 24 months in the absence of disease progression or unacceptable toxicity. Placebo: 1 tablet daily Digital mammography: Correlative studies immunohistochemistry staining method: Correlative Studies pharmacological study: Correlative Studies laboratory biomarker analysis: Correlative Studies protein expression analysis: correlative studies pharmacogenomic studies: correlative studies questionnaire administration: Ancillary studies Fine needle aspiration Quality of Life Assessment: Ancillary Studies
38
Total72

Baseline characteristics

CharacteristicArm I (Tamoxifen Citrate)TotalArm II (Placebo)
Age, Continuous43.7 years43.8 years44.1 years
Ethnicity (NIH/OMB)
Hispanic or Latino
3 Participants8 Participants5 Participants
Ethnicity (NIH/OMB)
Not Hispanic or Latino
31 Participants64 Participants33 Participants
Ethnicity (NIH/OMB)
Unknown or Not Reported
0 Participants0 Participants0 Participants
Race (NIH/OMB)
American Indian or Alaska Native
0 Participants0 Participants0 Participants
Race (NIH/OMB)
Asian
2 Participants3 Participants1 Participants
Race (NIH/OMB)
Black or African American
2 Participants3 Participants1 Participants
Race (NIH/OMB)
More than one race
0 Participants0 Participants0 Participants
Race (NIH/OMB)
Native Hawaiian or Other Pacific Islander
0 Participants0 Participants0 Participants
Race (NIH/OMB)
Unknown or Not Reported
0 Participants0 Participants0 Participants
Race (NIH/OMB)
White
30 Participants66 Participants36 Participants
Region of Enrollment
Canada
1 participants3 participants2 participants
Region of Enrollment
United States
33 participants69 participants36 participants
Sex: Female, Male
Female
34 Participants72 Participants38 Participants
Sex: Female, Male
Male
0 Participants0 Participants0 Participants

Adverse events

Event typeEG000
affected / at risk
EG001
affected / at risk
deaths
Total, all-cause mortality
0 / 340 / 38
other
Total, other adverse events
26 / 3425 / 38
serious
Total, serious adverse events
2 / 343 / 38

Outcome results

Primary

Mammographic Breast Density

Mammographic density was quantified as percentage of fibroglandular tissue. Using an intention-to-treat analysis, mammographic breast density (MBD) was compared between patients in the low dose tamoxifen intervention and placebo group by applying the linear mixed effects model for normally distributed data.

Time frame: At year two post treatment

ArmMeasureValue (LEAST_SQUARES_MEAN)Dispersion
Arm I (tamoxifen citrate)Mammographic Breast Density45.2 percentage of fibrogladular tissueStandard Error 2.4
Arm II (placebo)Mammographic Breast Density48.6 percentage of fibrogladular tissueStandard Error 2.5
p-value: 0.05Mixed Models Analysis
Secondary

Biomarker Levels

Total cholesterol, low and high density lipoprotein, triglycerides, and anti-thrombin III enzymatic assay measurements will be treated as continuous variables. Transformed to normality as appropriate, the linear mixed effects model will be applied, using the unstructured mean model and linear in time model to assess the effects of low-dose tamoxifen on these measurements over time.

Time frame: Up to 2 years

ArmMeasureGroupValue (LEAST_SQUARES_MEAN)Dispersion
Arm I (tamoxifen citrate)Biomarker LevelsLow-density lipoprotein105.4 mg/dLStandard Error 5.7
Arm I (tamoxifen citrate)Biomarker LevelsTriglycerides138.1 mg/dLStandard Error 13.2
Arm I (tamoxifen citrate)Biomarker LevelsHigh-density lipoprotein57.6 mg/dLStandard Error 3
Arm I (tamoxifen citrate)Biomarker LevelsAnti-thrombin III89.3 mg/dLStandard Error 5.4
Arm I (tamoxifen citrate)Biomarker LevelsTotal Cholesterol189.9 mg/dLStandard Error 7.1
Arm II (placebo)Biomarker LevelsAnti-thrombin III98.1 mg/dLStandard Error 5.7
Arm II (placebo)Biomarker LevelsTotal Cholesterol192.5 mg/dLStandard Error 7.2
Arm II (placebo)Biomarker LevelsLow-density lipoprotein108.6 mg/dLStandard Error 5.8
Arm II (placebo)Biomarker LevelsHigh-density lipoprotein56.5 mg/dLStandard Error 3
Arm II (placebo)Biomarker LevelsTriglycerides116.6 mg/dLStandard Error 13.5
p-value: >0.05Mixed Models Analysis
Secondary

Biomarker Levels - Alkaline Phosphatase

Serum bone-specific alkaline phosphatase measurements will be treated as continuous variables. Transformed to normality as appropriate, the linear mixed effects model will be applied, using the unstructured mean model and linear in time model to assess the effects of low-dose tamoxifen on these measurements over time.

Time frame: Up to 2 years

ArmMeasureValue (LEAST_SQUARES_MEAN)Dispersion
Arm I (tamoxifen citrate)Biomarker Levels - Alkaline Phosphatase12.2 ug/LStandard Error 0.7
Arm II (placebo)Biomarker Levels - Alkaline Phosphatase12.4 ug/LStandard Error 0.7
p-value: 0.739Mixed Models Analysis
Secondary

Biomarker Levels - Urine N-telopeptide

Urine n-telopeptide measurements will be treated as continuous variables. Transformed to normality as appropriate, the linear mixed effects model will be applied, using the unstructured mean model and linear in time model to assess the effects of low-dose tamoxifen on these measurements over time.

Time frame: Up to 2 years

ArmMeasureValue (LEAST_SQUARES_MEAN)Dispersion
Arm I (tamoxifen citrate)Biomarker Levels - Urine N-telopeptide33.1 nM Bone Collagen Equiv. / nM CreatinineStandard Error 3.6
Arm II (placebo)Biomarker Levels - Urine N-telopeptide32.0 nM Bone Collagen Equiv. / nM CreatinineStandard Error 3.8
p-value: 0.8315Mixed Models Analysis
Secondary

Insulin Growth Factor Levels (IGF1)

IGF1 will be treated as a continuous measure. The linear mixed effects model for between group comparisons of measures from 3 time points will be applied. The unstructured mean model and linear in time model will be employed.

Time frame: Up to 2 years

ArmMeasureValue (LEAST_SQUARES_MEAN)Dispersion
Arm I (tamoxifen citrate)Insulin Growth Factor Levels (IGF1)144.3 ng/mLStandard Error 7.1
Arm II (placebo)Insulin Growth Factor Levels (IGF1)162.3 ng/mLStandard Error 7.2
p-value: 0.0266Mixed Models Analysis
Secondary

Insulin Growth Factor Levels (IGF3 )

IGF3 will be treated as a continuous measure. The linear mixed effects model for between group comparisons of measures from 3 time points will be applied. The unstructured mean model and linear in time model will be employed.

Time frame: Up to 2 years

ArmMeasureValue (LEAST_SQUARES_MEAN)Dispersion
Arm I (tamoxifen citrate)Insulin Growth Factor Levels (IGF3 )4716.0 ng/mLStandard Error 168
Arm II (placebo)Insulin Growth Factor Levels (IGF3 )4315.2 ng/mLStandard Error 170.8
p-value: 0.071Mixed Models Analysis
Secondary

Number of Grade 2-4 Toxicities

Will be tabulated by treatment arm. Differences by treatment arm will be evaluated using Fisher exact tests.

Time frame: Up to 2 years

ArmMeasureValue (NUMBER)
Arm I (tamoxifen citrate)Number of Grade 2-4 Toxicities77 Adverse Events
Arm II (placebo)Number of Grade 2-4 Toxicities40 Adverse Events
p-value: 0.12Fisher Exact
Secondary

Number of Participants With Different Patient Reported Symptoms, Measured by Questionnaire

The outcomes will be scored as a 5-point Likert-type scale (0-4) in response to questions on how much the patients are bothered by certain symptoms. The questionnaire will be administered every 6 months. The responses will be treated as normally distributed, as ordinal or dichotomized variable, and the linear mixed effects of general linear mixed model (GLMM) methods will be applied to compare changes between treatment groups. Piecewise models will also be fitted with join point at 6 months, considering linear and curvilinear trajectories between 6 and 24 month time points.

Time frame: Up to 2 years

Population: Symptoms with \>10% prevalence are reported; patients were dichotomized into 2 groups: those that rated the symptom as moderately or extremely bothersome vs. slightly or quite a bit bothersome

ArmMeasureGroupValue (NUMBER)
Arm I (tamoxifen citrate)Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireInterrupted sleep16 participants
Arm I (tamoxifen citrate)Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireGeneral aches or pains14 participants
Arm I (tamoxifen citrate)Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireHot flashes13 participants
Arm I (tamoxifen citrate)Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireJoint pain or stiffness12 participants
Arm I (tamoxifen citrate)Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireFeeling unusually tired12 participants
Arm I (tamoxifen citrate)Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireHeartburn and/or acid stomach11 participants
Arm I (tamoxifen citrate)Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireHeadaches11 participants
Arm I (tamoxifen citrate)Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireMuscle cramps or soreness11 participants
Arm II (placebo)Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireMuscle cramps or soreness8 participants
Arm II (placebo)Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireInterrupted sleep16 participants
Arm II (placebo)Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireFeeling unusually tired10 participants
Arm II (placebo)Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireGeneral aches or pains8 participants
Arm II (placebo)Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireHeadaches14 participants
Arm II (placebo)Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireHot flashes12 participants
Arm II (placebo)Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireHeartburn and/or acid stomach10 participants
Arm II (placebo)Number of Participants With Different Patient Reported Symptoms, Measured by QuestionnaireJoint pain or stiffness9 participants
p-value: >0.05Chi-squared
Secondary

Percentage of Pills Taken Out of the Total Prescribed

The number of pills taken out of the total prescribed in a 3-month period will be modeled as a random effects binomial regression model. The binomial rates from 8 time points (month 3-24) will be modeled as unstructured mean model with 7 indicator variables as well as polynomial models over time. The random-intercept and the random intercept and slope models will be considered. The significance of the time indicators or parameters by treatment interaction will be evaluated for treatment difference in compliance.

Time frame: Up to 2 years

ArmMeasureValue (MEDIAN)
Arm I (tamoxifen citrate)Percentage of Pills Taken Out of the Total Prescribed97.5 percentage of pills taken
Arm II (placebo)Percentage of Pills Taken Out of the Total Prescribed96.7 percentage of pills taken
p-value: 0.78Wilcoxon (Mann-Whitney)

Source: ClinicalTrials.gov · Data processed: Feb 4, 2026