Intensity Modulated Radiotherapy (IMRT) vs. 3D-conformal Accelerated Partial Breast Irradiation (APBI) for Early Stage Breast Cancer After Lumpectomy

Inclusion Criteria:

Histologically confirmed disease (AJC Classification): Tis, T1, T2 (≤ 3.0 cm), N0, M0.
Microscopic multifocal disease is only allowed when the entire span of identified disease measures 3.0 cm or less.
Negative surgical margins ( ≥ 0.2 cm) after final surgery.
Subjects with infiltrating lobular histologies or high nuclear grade DCIS will be required to have breast MRI scanning as part of the initial staging to verify localized disease.
Subjects with DCIS will be included in the study only if they had an MRI prior to lumpectomy.
Findings on MRI scanning revealing relevant suspicion of disease outside of planned lumpectomy volume should be further evaluated by ultrasound and, if necessary biopsy, to exclude multicentric/multifocal disease.
Subjects with malignant calcifications on mammography will be required to have repeat mammography after surgery to ensure removal of all malignant calcifications.
Willing to complete additional screening requirements and meet eligibility criteria as defined in protocol Sec. 4.4.
Successful placement of fiducial markers for IGRT requiring nonmigrating fiducials.
PTV to ipsilateral breast ratio (IBR) ≤ 25 %.
Radiotherapy anticipated to begin within 10 weeks of lumpectomy or re-excision of margins.

Exclusion Criteria:

Pregnancy or breast-feeding.
Have collagen-vascular disease.
Inadequate surgical margins ( < 0.2 cm) after final surgery.
Subjects with persistent malignant/suspicious micro-calcifications.
Gross multifocal disease and microscopic disease greater than 3.0 cm.