The purpose of this study is to test the ability of a breast MRI biopsy to accurately diagnose a complete tumor response to the neoadjuvant chemotherapy (NAC) that the patient just finished. Numerous studies have shown that MRI has the highest accuracy for diagnosing a complete tumor response. The investigator wants to see if in a certain group of women who's breast cancer is no longer visible on the post-treatment MRI that the biopsy specimens from a MRI guided biopsy will accurately diagnose a complete tumor response to treatment which may in the future make breast surgery unnecessary in some women.

Inclusion Criteria:

• Women age 18 years or older
• Confirmed histologic diagnosis of operable HER2 overexpressing (ER<10%, PR<10%, and HER2 2+ or FISH amplified) OR triple negative (ER<10%, PR<10%, and HER2 0/1+ or 2+/FISH not amplified) OR ER positive invasive ductal or invasive lobular breast cancer including MSKCC pathology confirmation
• Operable breast cancer treated with NAC undergoing either breast conservation or total Mastectomy who have had a post-NAC clinical bilateral breast MRI demonstrating a complete imaging response, which is defined as no residual tumor enhancement.
• No indication of distant metastases (M0)
• Tumor site amenable to MRI guided biopsy as determined by the radiologist
• Definitive surgery being performed at MSKCC within within 0-60 days of completing NAC
• ECOG performance status score of 0 to ≤ 2 and or KPS performance status score of 80% to 100%
• Women of childbearing potential (WOCBP) must not be pregnant.
• Women must not be breastfeeding
• Willing and able to provide informed consent and adhere to the study visit schedule and plan as specified in this protocol

Exclusion Criteria:

• Medical history and concurrent disease:

  • Prior history of treated breast cancer
  • Any underlying medical or psychiatric conditions, which in the opinion of the investigator, will make performing the study intervention hazardous or obscure the interpretation of the results

• Prohibited Treatments and/or Therapies:

  • Prior history of breast cancer surgery and/or radiotherapy.

Breast Cancer