Whole Breast Irradiation vs Twice Daily vs. Once Daily Accelerated Partial Breast Irradiation

Inclusion Criteria

• •Tumor characteristics
• •Histologically confirmed invasive adenocarcinoma of the breast
• •Tumors must be ≤ 3 cm. Gross disease must be unifocal. Negative lymph nodes
• •Hormone receptor status:
• •Estrogen receptor (ER) status known Progesterone status known if ER analysis is negative Marginal or borderline results are considered positive Surgery
• •Tumor removed with conservative breast surgery with adequate margin
• •Re-excision of surgical margins allowed
• •No prior breast implants
• •Prior axillary staging required for patients including 1 of the following:
• •* Sentinel node biopsy alone (if sentinel node is negative)
• •* Sentinel node biopsy followed by axillary dissection if sentinel node is positive)
• •* Axillary dissection alone with ≥ 6 axillary nodes
• •Target lumpectomy cavity clearly delineated AND target lumpectomy/whole breast reference volume ≤ 30% based on postoperative pre-randomization CT scan
• •Final surgery (i.e., lumpectomy, re-excision of margins, or axillary staging procedure) within the past 42 days
• •No prior biologic therapy for this malignancy Chemotherapy
• •No prior chemotherapy for this malignancy
• •No concurrent chemotherapy during study radiotherapy Endocrine therapy
• •No prior hormonal therapy for this malignancy
• •Concurrent hormonal therapy allowed provided it is not administered during chemotherapy
• •No concurrent raloxifene, tamoxifen, or other selective estrogen receptor modulating drugs
• •No concurrent hormone replacement therapy Radiotherapy
• •No prior radiotherapy for this malignancy
• •No prior breast or thoracic radiotherapy
• •No concurrent regional nodal irradiation Other
• •No other concurrent anticancer therapy Menopausal status
• •Premenopausal or postmenopausal Performance status
• •WHO 0-1 Other
• •Not pregnant or nursing
• •Negative pregnancy test
• •Fertile patients must use effective non-hormonal contraception