Lack of funding

Tamoxifen is a hormonal treatment for breast cancer. It prevents recurrent disease and decreases death. Tamoxifen is given to women with and at high risk for breast cancer. These women also commonly have breast MRI to monitor for breast cancer. Some features of normal breast tissue visible on breast MRI change depending on patient hormonal status. It has been questioned if hormonal changes due to tamoxifen are seen on breast MRI. Pilot data suggests this is true. If tamoxifen causes changes in normal breast tissue on MRI, more study could be done looking at whether breast MRI could tell us anything about whether tamoxifen is working.

This study is being done to see if tamoxifen changes normal breast tissue on MRI. It will also look at if other factors like taking anti-depressants or gene type have any effect.

Inclusion Criteria:

• Females with stage 0-3 breast cancer who have had or are planned to have a breast MRI within 1 year prior to starting tamoxifen
• Premenopausal status is defined as intact ovaries and still menstruating
• Clinical and MRI follow-up planned at MSKCC or MCKCC regional facility
• Willing and able to undergo all study procedures

Exclusion Criteria:

• Contraindication to breast MRI (such as non-compatible cardiac pacemakers or intracranial vascular clips, allergy to Gadolinium)
• Bilateral breast cancer or treatment such as:
• History of or planned bilateral breast irradiation
• History of or planned bilateral mastectomy
• Bilateral breast cancer
• History of unilateral mastectomy or radiation treatment with contralateral breast cancer
• Taking chemo- or hormonal therapy at the time of the baseline breast MRI
• Estrogen and progesterone receptor negative breast cancer
• GFR less than GFR < 30 mL/min/1.73m2
• Postmenopausal women
• Pregnant and/or nursing women
• Less than 21 years of age

Eligible premenopausal patients with stage 0-3 breast cancer for whom MRI staging is planned will be enrolled.