RATIONALE: Radiation therapy uses high-energy x-rays to kill tumor cells. Giving radiation therapy in different ways and giving it after surgery may kill any tumor cells that remain after surgery.

PURPOSE: This randomized clinical trial is studying radiation therapy to see how well it works in treating women with localized breast cancer.

OBJECTIVES:

• Compare late normal tissue effects of standard vs 2 different dose levels of hypofractionated adjuvant whole breast radiotherapy, in terms of changes in photographic breast appearance, in women with localized breast cancer who are at average or low risk of recurrence.
• Compare tumor control in patients treated with these regimens.

OUTLINE: This is a randomized, multicenter study. Patients are stratified according to participating center. Patients are randomized to 1 of 3 treatment arms.

• Arm I (control): Patients undergo standard radiotherapy 5 days a week for 5 weeks.
• Arm II: Patients undergo hypofractional radiotherapy once a week for 5 weeks.
• Arm III: Patients undergo hypofractional radiotherapy (at a lower dose than arm II) once a week for 5 weeks.

After completion of study treatment, patients are followed annually for 5-10 years.

PROJECTED ACCRUAL: A total of 900 patients (300 per treatment arm) will be accrued for this study within 12 months.

DISEASE CHARACTERISTICS:

• Diagnosis of invasive carcinoma of the breast

  • Localized disease

    • Pathological tumor size < 3.0 cm in diameter
    • Axillary node negative

• At average or low risk of local tumor recurrence

• Must have undergone prior breast-preserving surgery

  • No prior mastectomy
  • Complete microscopic resection of tumor

• Hormone receptor status:

  • Not specified

PATIENT CHARACTERISTICS:

Age

• 50 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

Other

• Fertile patients must use effective contraception

PRIOR CONCURRENT THERAPY:

Biologic therapy

• Not specified

Chemotherapy

• No prior neoadjuvant or adjuvant cytotoxic chemotherapy

Endocrine therapy

• Not specified

Radiotherapy

• No concurrent lymphatic radiotherapy
• No concurrent radiotherapy boost to the breast

Surgery

• See Disease Characteristics