Partial Breast Irradiation in a Low-risk Population Screened With MRI

Inclusion Criteria:

• Stage 0 or I breast carcinoma
• 40 years or older
• Post menopausal
• Lumpectomy with clear margins (>2mm)
• Patients with invasive disease must have undergone an axillary staging by axillary dissection (with a minimum of 6 axillary nodes) or sentinal node biopsy
• Gross disease must be unifocal with pathological tumor size 2cm or less
• Target lumpectomy cavity must be clearly marked with surgical clips (the target lumpectomy cavity/whole breast reference volume must be <=30% based on the postoperative imaging)
• Bilateral MRI of the breasts within previous 6 months of radiation therapy (RT) planning
• If patient is eligible based on postoperative imaging, partial breast irradiation (PBI) is judged to be technically deliverable
• Patients with a history of malignancies are eligible if they have stable disease as determined by their attending oncologist
• Patient must have signed the consent form

Exclusion Criteria:

• Men are not eligible
• Patients with Stage II, II, or IV breast cancer
• Pre- or peri-menopausal patients
• Patients with positive lymph nodes
• Patients with suspicious microcalcifications, densities, or palpable abnormalities unless biopsied and found to be benign
• Patients with multifocal, multicentric, or bilateral breast cancer
• Surgical margins that cannot be microscopically assessed or are positive at pathological evaluation
• Patients with a history of breast cancer
• Clear delineation of the extent of the target lumpectomy cavity is not possible
• Breast implants (patients who have had implants removed are eligible)
• Prior breast or thoracic RT for any condition