Randomized Study on Postmenopausal Women With Early Stage Breast Cancer: WBI Versus APBI

Randomized Study on Postmenopausal Women With Early Stage Breast Cancer: Adjuvant Hypofractionated Whole Breast Irradiation (WBI) Versus Accelerated Partial Breast Irradiation (APBI)

Selected patients with early stage breast cancer undergone conservative surgery were randomized in two arms: Hypofractionated Whole Breast Irradiation versus Accelerated Partial Breast Irradiation.

Patients treated with Hypofractionated Whole Breast Irradiation (WBI) received SIB irradiation of the whole breast and surgical bed at two different dose levels. Dose prescription was 40.5 Gy to PTVWB and 48.0 Gy to PTVboost in 15 fractions over 3 weeks, with simultaneous integrated boost delivering 2.7 and 3.2Gy/fraction for each PTV respectively. Daily image guided radiotherapy (IGRT) were generated before each treatment session in each patient to verify the set-up.

Accelerated Partial Breast Irradiation (APBI) using external intensity -modulated radiotherapy (VMAT RA) was delivered at a dose of 30 Gy in five 6-Gy/day fractions over 10 days (every other day) with IGRT at each treatment.

Inclusion Criteria:

• 55< Age <70
• Tumor size ≤ 2 cm
• pN0 (SN biopsy or ALND)
• ER/PgR positive
• Margins > 5 mm (either at initial surgery or at re-excision)
• Clips placed in the surgical bed (minimum of 4 clips)
• Unicentric only
• No lymphovascular invasion
• Any grade
• No extensive intraductal component (>25%)
• Written informed consent

Exclusion Criteria:

• Prior thoracic radiation therapy
• Oncoplastic surgery / No clips in the surgical bed
• Multicentric cancer
• Autoimmune disease, vasculitis, collagenopathy or scleroderma that may predispose to late sequelae