Inclusion Criteria:

• Women > 35 years old and < 75 years old with at least one of the following:
  • A NCI-BCRAT 5 year risk of ≥ 3% which corresponds to the level in which there is moderate evidence of treatment benefit outweighing risk according to the US Preventative Services Task Force; or
  • IBIS (Tyrer-Cuzik) score for the 10 year risk of breast cancer of ≥ 8%;
  • History of atypical ductal hyperplasia or atypical lobular hyperplasia with a BCRAT ≥ 3% or IBIS ≥ 8%;
  • History of  lobular carcinoma in situ with a BCRAT ≥ 3% or IBIS ≥ 8%.

OR

• Women ≥ 18 years old or ≤ 75 years old with a:
  • BRCA 1 or 2  mutation;
  • CHEK 2;
  • PALB 2;
  • ATM; or other hereditary breast mutation carrier per investigator; 

AND

• Able to participate in all aspects of the study.
• Understand and sign the study informed consent. 

Exclusion Criteria:

• 1. 1.  
• Women whose BCRAT falls below the threshold (< 3% 5-year risk) of moderate benefit according to the US Preventative Task Force AND Women whose IBIS score is < 8% for the 10 year risk.
• Women with known contra-indications to Tamoxifen, raloxifene ,exemestane, or anastrazole.
• Current or prior use of Tamoxifen, raloxifene, exemestane or anastrazole for ≥ 6 months.
• Unable to give informed consent.
• Prior history of invasive breast cancer, ductal carcinoma in situ or other breast cancers.
• Prior bilateral  prophylactic mastectomy.
• Women who are currently pregnant.