RATIONALE: Radiation therapy uses high-energy x-rays to damage tumor cells. It is not yet known which regimen of radiation therapy is more effective following surgery for breast cancer.

PURPOSE: Randomized phase III trial to compare the effectiveness of two different regimens of radiation therapy following surgery in treating women who have early stage breast cancer.

OBJECTIVES:

• Determine the benefits of radiotherapy schedules using fraction sizes larger than 2.0 Gy in terms of normal tissue responses, local-regional tumor control, quality of life, and economic consequences in women prescribed postoperative radiotherapy for early stage breast cancer.

OUTLINE: This is a randomized, multicenter study. Patients are stratified according to center, type of surgery (mastectomy vs local excision), and breast boost (yes vs no). Patients are randomized to 1 of 3 treatment arms.

• Arm I: Patients receive radiotherapy 5 times a week for 5 weeks for a total dose of 50 Gy.
• Arm II: Patients receive radiotherapy 5 times a fortnight (i.e., Monday/Wednesday/Friday/Tuesday/Thursday/Monday, etc.) for 13 fractions over 5 weeks for a total dose of 41.6 Gy.
• Arm III: Patients receive radiotherapy as in arm II for a total dose of 39 Gy. A breast boost is recommended in all arms for patients with microscopic evidence of invasive or in situ cancer at, or within 1 mm of, a resection margin. These patients receive radiotherapy for 5 fractions in 1 week for a total boost dose of 10 Gy.

Quality of life is assessed at baseline and then at 6, 12, 24, and 60 months.

Patients are followed annually for up to 20 years.

PROJECTED ACCRUAL: A total of 2,010 patients (670 per arm) will be accrued for this study.

DISEASE CHARACTERISTICS:

• Histologically confirmed invasive unilateral breast cancer that is considered operable

  • T1-3, N0-1, M0 at presentation

• Complete macroscopic excision of tumor by breast conserving surgery or mastectomy

• No immediate breast reconstruction

• No requirement for axillary radiotherapy after greater than a Level 1 axillary dissection or after greater than 10 lymph nodes have been removed

• Not enrolled on SECRAB or OSCAR trials

• Hormone receptor status:

  • Not specified

PATIENT CHARACTERISTICS:

Age:

• 18 and over

Sex:

• Female

Menopausal status:

• Not specified

Performance status:

• Not specified

Life expectancy:

• Not specified

Hematopoietic:

• Not specified

Hepatic:

• Not specified

Renal:

• Not specified

PRIOR CONCURRENT THERAPY:

• Prior neoadjuvant, or primary medical, therapy allowed provided subsequent surgery confirms complete macroscopic excision of residual primary tumor

Biologic therapy:

• Not specified

Chemotherapy:

• At least 2 weeks since prior cytotoxic agents
• No concurrent chemotherapy

Endocrine therapy:

• Not specified

Radiotherapy:

• See Disease Characteristics

Surgery:

• See Disease Characteristics