Preoperative Stereotactic Ablative Body Radiotherapy (SABR) for Early-Stage Breast Cancer

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.