Accelerated Partial Breast Irradiation by Mammosite and intensity modulated radiotherapy is safe and effective in patients with early stage breast cancer resected by lumpectomy.

Inclusion Criteria:

• Be a Tis, T1, N0, M0 AJC Classification
• Have negative surgical margins (> or = 2 mm) after final surgery
• Should have adequate skin spacing between balloon surface and surface the skin (> 7 mm)*
• Patients with infiltrating lobular histologies should have breast MRI scanning as part of the initial staging to verify localized T1, or Tis disease
• Multifocal findings (define as 2 or more breast quadrants) on MRI scanning should be further evaluated by ultrasound and, if necessary biopsy, to exclude multiquadrant disease.

Exclusion Criteria:

• Be pregnant or breast-feeding
• Have collagen-vascular disease
• Inadequate surgical margins (< 2 mm)
• Patients with malignant/suspicious calcifications