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Evaluation of Diindolylmethane Supplementation to Modulate Tamoxifen Efficacy in Breast Cancer The Diindolylmethane Efficacy Study

Phase 2/Phase 3
19 Years
Open (Enrolling)
Ductal Breast Carcinoma in Situ, Lobular Breast Carcinoma in Situ, Recurrent Breast Cancer, Stage IA Breast Cancer, Stage IB Breast Cancer, Stage II Breast Cancer, Stage IIIA Breast Cancer

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Trial Information

Evaluation of Diindolylmethane Supplementation to Modulate Tamoxifen Efficacy in Breast Cancer The Diindolylmethane Efficacy Study


I. Assess change in breast density using mammogram-based breast density measures as well as
a novel, quantitative fat-water ratio breast magnetic resonance imaging (FWR-MRI).

II. Evaluate the effect of an escalating daily dose of DIM on serum steroid hormones
(estrogen, sex hormone binding globulin [SHBG]) and urinary 2-hydroxyestrone:16
alpha-hydroxyestrone (2OHE1:16 alpha OHE1) ratio as well as serum tamoxifen (TAM)
metabolites (endoxifen). The study will be initiated at a dose of 75 mg twice daily (BID)
(total daily dose of 150 mg) for the first 10 study participants and then the dose will be
escalated to 150 mg DIM BID (total daily dose of 300 mg) if no treatment-related serious
adverse events (SAEs) are reported in the initial 10 subjects thru 3 months of treatment.

III. Expand on currently available toxicity and safety of DIM-TAM combination by assessing
reports of treatment associated side effects/adverse events including TAM-associated
endometrial toxicity (self-reported vaginal bleeding patterns and physician ordered vaginal
ultrasound), chemistry profiles, Functional Assessment of Cancer Therapy-Endocrine Subscale
(FACT-ES) scores and standard Common Terminology Criteria for Adverse Events (CTCAE)


I. Collect fine-needle aspiration breast tissue samples (in a subset) and blood samples (all
participants) in order to explore change in mammary gland tissue architecture and
cellularity; and tissue markers and their association with change in breast density and to
explore changes in biomarkers of disease risk (e.g. cyclooxygenase-2 [COX-2],
deoxyribonucleic acid [DNA] adducts, oxidative stress, inflammation, etc) over time (pre and
post treatment) in both study arms.

OUTLINE: Patients are randomized to 1 of 2 treatment arms.

ARM I: Patients receive diindolylmethane orally (PO) BID for approximately 36 months.

ARM II: Patients receive placebo PO BID for approximately 36 months.

In both arms, treatment continues in the absence of unacceptable toxicity.

After completion of study treatment, patients are followed up periodically.

Inclusion Criteria:

- Prescribed TAM as adjuvant therapy for early stage (0, I, II, IIIa) breast cancer or
as chemoprevention in women at high risk for breast cancer

- New or planned prescription of TAM therapy; ineligible for randomization until on TAM
for > 3 months with the expectation to continue use for > 18 months

- Mammogram with Breast Imaging Reporting and Data System (BIRADS) score of >= 2;
(equivalent to the following and similar breast density descriptive terms found in
mammogram reports: 2 = scattered fibroglandular elements/densities; 3 =
heterogeneously dense tissue; 4 = extremely dense tissue)

- Breast cancer surgery resulted in intact contralateral breast for mammography/MRI

- No use of soy-based dietary supplements or willingness to discontinue use, complete a
4-week wash-out period, prior to randomization, and refrain from use during trial

- If pre-menopausal, non-pregnant (confirmed with urinary pregnancy test); practicing
birth control or s/p oophorectomy

- Able to complete study run-in activities, including taking study-provided placebo
pill twice daily (AM & PM) and recording pill intake and any symptoms experienced on
a study calendar, with a compliance rate of at least 80%

- Normal blood chemistry test that includes sodium and specific kidney and liver
function tests (creatinine, alanine amino transferase-ALT, aspartate amino
transferase-AST) within 30 days of study enrollment; (Informed Consent Form signed)

- No history of hyponatremia

Type of Study:


Study Design:

Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Investigator), Primary Purpose: Treatment

Outcome Measure:

Mammographic Density

Outcome Description:

MRI imaging will be performed to assess mammographic density.

Outcome Time Frame:

Up to 18 months

Safety Issue:


Principal Investigator

Cynthia Thomson

Investigator Role:

Principal Investigator

Investigator Affiliation:

University of Arizona


United States: Federal Government

Study ID:




Start Date:

February 2011

Completion Date:

Related Keywords:

  • Ductal Breast Carcinoma in Situ
  • Lobular Breast Carcinoma in Situ
  • Recurrent Breast Cancer
  • Stage IA Breast Cancer
  • Stage IB Breast Cancer
  • Stage II Breast Cancer
  • Stage IIIA Breast Cancer
  • Breast Neoplasms
  • Carcinoma
  • Carcinoma in Situ
  • Carcinoma, Intraductal, Noninfiltrating
  • Carcinoma, Ductal, Breast
  • Carcinoma, Lobular



Arizona Cancer CenterTucson, Arizona  85724