The purpose of this study is to determine whether adding DIM supplement will decrease breast density among female BRCA mutation carriers in two years.

The Research Question: In female BRCA mutation carriers, will adding DIM (100mg*1/d, a nutritional supplement), decrease breast density in two years?

Study design: A single center single arm prospective interventional study of the use of DIM to decrease risk of breast cancer among female BRCA carriers.

Study population: Subjects will be female carriers of a BRCA mutation and have more than 10% mammographic breast density at baseline.

Intervention: DIM supplement (100mg*1/d).

Study Time line: This will be a 2 years study. At initiation a breast mammography will be performed and eligibility assessed. Follow-up visits will occur every 4 months and quality of life questionnaires as well as adherence to DIM supplementation will be assessed. At the initiation and every 4 months blood and urine samples will be collected for Estrogen profile. At 12 and 24 months a mammography will be performed to verify changes in breast density.

Primary Endpoint: A decrease of more than 10% in breast density compared to baseline, following DIM supplementation intervention among female BRCA carriers.

Study impact: Decrease in mammographic breast density was shown to be a good marker for lower risk of breast cancer. This study has the potential to dramatically impact the management of female BRCA carriers. If we prove that by adding a food supplement breast density is decreased, we will change standard of care in these woman. In addition, the urine and blood samples collected during the study will be used for future translational research on the pathogenesis of breast cancer.

Inclusion Criteria:

• Women who carrier the BRCA 1\2 mutation.
• No history of breast or ovarian malignancy.
• i. Baseline mammographic breast density is more than 10% OR ii. Baseline breast MRI with density or enhancement ≤ 2.
• Age 18-70.
• Absence of any psychological, familial, sociological or geographical situation potentially hampering adherence to the study protocol and follow-up schedule.
• Informed written consent must be signed according to ICH/EU GCP, before subject registration.

Exclusion Criteria:

• Women who have undergone preventive breast reduction.
• Breast imaging demonstrating a lesion suspected to be cancerous.
• Breast feeding or Pregnancy or planning to get pregnant.
• Known allergy to DIM and its ingredients.