Real-Time MRI-Guided 3-Fraction Accelerated Partial Breast Irradiation in Early Breast Cancer

Inclusion Criteria:

For all participants

Participants should have no contraindications to undergo MRI scan as part of radiotherapy planning and treatment.
Lumpectomy cavity must be clearly visible on CT and MRI scan at radiotherapy simulation.
Pregnancy test negative in women of child bearing potential (WOCBP).
The participant must consent to be in the study and must have signed an approved consent form conforming with institutional guidelines.
Participants with a history of non-breast malignancies are eligible if they have been disease-free for 5 or more years prior and are deemed by their physician to be at low risk for recurrence. Participants with the following cancers are eligible if diagnosed and treated within the past 5 years: carcinoma in situ of the cervix, carcinoma in situ of the colon, melanoma in situ, and basal cell and squamous cell carcinoma of the skin.

For participants with Invasive Carcinoma

Suitable:

Age: >=50 years

Margins: Negative by at least 2 mm
T Stage: Tis or T1

Cautionary:

Age: 40-49 years

Margins: Negative by at least 2 mm
T Stage: Tis or T1 OR

Age: >=50 years IF participant has at least 1 of the pathologic factors below and does not have any "unsuitable" factors (below)

Pathologic Factors:

Size 2.1-3.0 cm (size of the invasive component)
T2
Close margins (<2 mm)
Limited/focal Lymphovascular Space Invasion (LVSI)
ER (-)
Clinically unifocal with total size 2.1-3.0 cm (Microscopic multifocality allowed, provided the lesion is clinically unifocal (a single discrete lesion by physical examination and ultrasonography/mammography) and the total lesion size (including foci of multifocality and intervening normal breast parenchyma) falls between 2.1 and 3.0 cm).
Invasive lobular histology
Extensive Intraductal Component (EIC) <=3 cm

For participants with DCIS

Suitable Criteria, DCIS allowed if all of the following are met:

Screen-detected
Low to intermediate nuclear grade
Size <=2.5 cm
Resected with margins negative at >=3mm OR

Cautionary Criteria:

Pure DCIS <=3 cm if "suitable" criteria not fully met

Exclusion Criteria (unsuitable criteria) :

Men are not eligible for this study.
BRCA1/2 mutation positivity.
Age < 40 years (American Society for Radiation Oncology (ASTRO) Unsuitable Criteria).
Positive resection margins on post operative pathology(ASTRO Unsuitable Criteria).
Palpable or radiographically suspicious ipsilateral or contralateral axillary, supraclavicular, infraclavicular, or internal mammary nodes, unless there is histologic confirmation that these nodes are negative for tumor.
Suspicious micro calcifications, densities, or palpable abnormalities (in the ipsilateral or contralateral breast) unless biopsied and found to be benign.
Non-epithelial breast malignancies such as sarcoma or lymphoma.
Proven multicentric carcinoma (invasive cancer or DCIS) (ASTRO Unsuitable Criteria).
Pure DCIS >3 cm in size (ASTRO Unsuitable Criteria).
Presence of extensive intraductal component >30mm (ASTRO Unsuitable Criteria).
Paget's disease of the nipple.
History of previous invasive breast cancer, DCIS, synchronous bilateral invasive or non-invasive breast cancer. (Participants with a history of LCIS treated by surgery alone are eligible.)
Surgical margins that cannot be microscopically assessed or are positive at pathologic evaluation.
Concurrent therapy with any hormonal agents such as raloxifene (Evista®), tamoxifen, Aromatase Inhibitors or other selective estrogen receptor modulators (SERMs), either for osteoporosis or breast cancer prevention or neoadjuvant therapy.
Breast implants.
Prior breast or thoracic radiotherapy for any condition or treatment plan that includes regional nodal irradiation.
Collagen vascular disease, specifically dermatomyositis with a creatinine phosphokinase level above normal or with an active skin rash, systemic lupus erythematosus, or scleroderma.
Pregnancy or lactation at the time of treatment. Women of reproductive potential must agree to use an effective non-hormonal method of contraception during therapy.
Psychiatric or addictive disorders or other conditions that, in the opinion of the investigator, would preclude the participant from meeting the study requirements.