Effect of Preoperative Breast MRI on Surgical Outcomes, Costs and Quality of Life of Women With Breast Cancer

• Female. Men are excluded from this study because the number of men with breast cancer is insufficient to provide a statistical basis for assessment of effects in this subpopulation of people with breast cancer.

• Pathologically confirmed diagnosis of breast cancer, clinical stage I-II (T1-3 N0 M0, T0-2 N1 M0). Diagnosis must be by needle biopsy; patients diagnosed by surgical excision are excluded.

• Patients must have either:

⁃ Estrogen receptor (ER) negative/progesterone receptor (PR) negative (\< 10% by immunohistochemistry IHC staining) and HER-2 negative breast cancer OR

• ER negative/PR negative (\< 10% by IHC staining) and HER-2 positive tumors

• HER-2 status will be determined as per the 2013 ASCO CAP guidelines:

∙ HER-2 is considered positive if there is IHC 3+ staining or ISH positive using either single probe ISH or dual probe ISH

‣ HER-2 is considered negative if there is IHC 0 or 1+ staining or ISH negative using either single probe ISH or dual probe ISH

• No patients with previous ipsilateral invasive breast cancer or ductal carcinoma in situ (DCIS)

• No patients with bilateral breast cancer

• No patients with known deleterious mutations in breast cancer (BRCA) genes

• No current history of receiving hormonal therapy, tamoxifen, and or aromatase inhibitors for therapeutic measures

• No history of chemotherapy for cancer within 6 months prior to registration

• No patients scheduled to receive neoadjuvant chemotherapy or partial breast irradiation following breast conserving surgery

• Eligible for BCT based on clinical examination, mammography and, if standard practice at a given institution, ultrasound and/or tomogram. Women who cannot be appropriately selected for BCT based on these standard imaging studies, and for whom additional imaging is recommended to clarify local disease extent, will not be eligible for this trial.

• No patients with multicentric or multifocal disease scheduled to undergo multiple lumpectomies. Multifocal disease that can be encompassed in a single operative bed can be enrolled.