no responders/lack of efficacy

This study involves a course of radiation to the tumor that is delivered BEFORE surgery. The type of radiation is called stereotactic ablative body radiation therapy (SABR). The purpose of this study is to evaluate the effects, good and/or bad, of pre-operative SABR specifically focusing on its ability to reduce the chances that additional breast surgery will be needed, reducing the amount of breast/heart/lung tissue that is irradiated, and to study the tumor-tissue effects of SABR. The usual treatment for patients with early-stage breast cancer who have breast-conserving treatment (BCT) is to receive radiotherapy AFTER surgery, targeting either the whole breast or part of the breast.

Inclusion Criteria:

• Understand and voluntarily sign an informed consent document prior to conducting any study related assessments or procedures.
• Histologically proven invasive adenocarcinoma of breast.
• Must have marker clip indicating location of target tumor in breast.
• Unifocal tumor less than or equal to 2 cm based on contrast-enhanced prone-breast MRI.
• Must be clinically and radiographically node negative (N0) to participate on this protocol. Clinically suspicious regional nodes by imaging or physical exam require biopsy evaluation to exclude disease involvement.
• Appropriate candidate for breast-conserving surgery based on multi-disciplinary assessment.
• Females age ≥ 50 years.
• Able to tolerate prone body positioning during radiation therapy.
• No prior ipsilateral-breast or thoracic radiotherapy.
• As defined on MRI, target lesion must be at least 10 mm distance from skin (defined as volume encompassing first 3 mm from breast surface).
• Must be estrogen receptor (ER) positive.
• Must be negative for Her-2 amplification. (Either 1+ on semi-quantitative evaluation of immunostain or negative by fluorescent in-situ hybridization).
• No implanted hardware or other material that would prohibit appropriate treatment planning or treatment delivery in the investigator's opinion.
• No history of an invasive malignancy (other than this breast cancer, or non-metastatic basal or squamous skin cancers) in the last 5 years.
• Must not have received nor be planned for neoadjuvant chemotherapy prior to SABR or surgery.
• ECOG performance status less than 2.
• Females of childbearing potential must have a negative urine pregnancy test prior to simulation and within seven days of SABR start.

Exclusion Criteria:

• Have invasive lobular carcinoma.
• Have a Tumor > 2 cm as measured on prone contrast-enhanced breast MRI.
• Have presence of histologically proven lymph node disease.
• Are not a candidate for breast conserving surgery.
• Have had prior ipsilateral-breast or thoracic radiotherapy.
• History of scleroderma or lupus erythematosus with either cutaneous manifestation or requiring active treatment.
• An MRI defined target tumor that is within 10 mm of skin (defined as volume encompassing first 3 mm from skin surface).
• Have amplification of Her-2 (Either 3+ by semi-quantitative immunostain or positive by Fluorescent in-situ hybridization (FISH)).
• Have implanted hardware or other material that would prohibit appropriate treatment planning or treatment delivery in the investigator's opinion.
• History of an invasive malignancy (other than this breast cancer, or non-metastatic basal or squamous skin cancers) in the last 5 years.
• Have received or plan to receive neoadjuvant chemotherapy either before radiotherapy or before surgery.
• A known carrier of BRCA1 or BRCA2 gene mutation.
• Pregnant or unwilling to undergo pregnancy screening.