A robust knowledge of how to reduce breast density could play a key role in breast cancer prevention in premenopausal women, but viable preventative targets to reduce breast density-associated breast cancer risk are yet to be developed. The investigators propose to investigate the effect of RANKL inhibition with denosumab on breast tissue markers in high-risk premenopausal women with dense breasts. Study findings could provide robust evidence to move forward with a clinical trial targeting RANKL inhibition in premenopausal breast cancer prevention.

Inclusion Criteria:

• Female.

• Premenopausal.

• At least 35 years of age.

• Dense breasts on routine mammogram.

• Willing to take calcium (1,200mg) and vitamin D (800 IU) daily.

• At increased risk for breast cancer using any of the following:

  • Positive family history of breast cancer
  • Breast cancer risk prediction models

• Able and willing to return for repeat biopsy.

• Able to understand and willing to sign an IRB-approved written informed consent document.

Exclusion Criteria:

• Current use of tamoxifen, aromatase inhibitors, or bisphosphonates.
• Concurrently participating in another cancer chemoprevention trial (unless no longer receiving the intervention).
• Pregnant or lactating.
• Recent tooth extraction or dental procedure.
• Unhealed and/or planned dental/oral surgery.
• History of osteonecrosis/osteomyelitis of the jaw.
• History of osteoporosis or severe osteopenia.
• Unable/unwilling to return for repeat biopsy.