Molecular Breast Imaging is a highly promising novel methodology for breast cancer detection. Preliminary patient studies with our dual-detector system indicate that this system is capable of reliably detecting very small (5-10 mm) malignant lesions in the breast. Besides the usefulness of Molecular Breast Imaging for tumor detection, we speculate that tumor uptake and washout may be predictors to response to neoadjuvant therapy for patients with the diagnosis of breast cancer. We propose that in patients with breast cancer who undergo neoadjuvant chemotherapy or neoadjuvant hormone therapy that molecular breast imaging is an accurate test for assessing response rate to neoadjuvant therapy.

Adjuvant therapy after surgery for breast cancer has provided significant benefits to patients at risk for relapse. However, the success of therapy for each individual patient will often take years to reveal. Preoperative (neoadjuvant) medical therapy is very potent as an initial treatment for inoperable and large operable breast cancers. Tumor regression can be achieved in the great majority of patients and downstaging frequently reduces the need for mastectomy and it has become clear that pathologic complete response is a good prognostic marker. Data from current trials suggest that survival is at least as good with preoperative as with postoperative neoadjuvant therapies (1). With this observation preoperative medical therapy has the advantage over post-operative neoadjuvant therapy that it can be used as a short term surrogate marker for long-term outcome. With this translational approach, the therapy for each patient can be more targeted and individualized leading to higher success rates; and further, new therapies for early breast cancer can be assessed much more quickly than is currently possible through protracted trials of neoadjuvant therapy (2). This approach is therefore being increasingly utilized in patients with lower stage breast cancers.

Inclusion Criteria:

• Women age 18 - 90
• Women with breast cancer scheduled to undergo neoadjuvant chemotherapy therapy or neoadjuvant hormone therapy
• Women who have undergone any breast imaging procedure, and in whom a repeat imaging procedure is planned prior to definite surgery

Exclusion Criteria:

• Pregnant or lactating
• Unable to understand or sign a consent form
• Physically unable to sit upright and still for 40 minutes