RATIONALE: Radiation therapy uses high-energy x-rays to damage tumor cells. It is not yet known whether radiation therapy after surgery is effective in preventing a recurrence of ductal carcinoma in situ.

PURPOSE: This randomized phase II trial is studying adjuvant radiation therapy to see how well it works compared to observation after surgery in treating women with estrogen receptor positive or progesterone receptor positive ductal carcinoma in situ and are also receiving either tamoxifen or anastrozole.

OBJECTIVES:

Primary

• Compare ipsilateral tumor relapse and breast cancer metastases in women with completely excised low-risk estrogen receptor- or progesterone receptor-positive ductal carcinoma in situ of the breast receiving adjuvant tamoxifen or anastrozole and treated with adjuvant radiotherapy vs observation alone.
• Compare the quality of life of patients treated with these regimens.

Secondary

• Determine the minimal surgical margins required to minimize the local recurrence rate in patients treated with these regimens.
• Identify molecular markers that predict ipsilateral tumor recurrence 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 2 treatment arms.

All patients receive adjuvant tamoxifen or anastrozole for 5 years.

• Arm I: Patients undergo radiotherapy 5 days a week for 3 or 5 weeks.
• Arm II: Patients undergo observation alone. Quality of life is assessed at baseline, at 6 months, and then at 1, 2, and 5 years.

Patients are followed every 6 months for 1 year and then annually for up to 10 years.

Peer Reviewed and Funded or Endorsed by Cancer Research UK

PROJECTED ACCRUAL: A total of 2,000 patients (1,000 per treatment arm) will be accrued for this study within 5 years.

DISEASE CHARACTERISTICS:

• Diagnosis of unifocal ductal carcinoma in situ of the breast without an invasive component

  • Microinvasion (defined as 1 or more foci of invasion each < 1 mm) allowed

• Prior complete microscopic excision (within the past 6 months) with a minimum radial margin of 1 mm by specimen x-ray required

• Maximum microscopic tumor diameter < 30 mm (< 15 mm if grade 3 tumor)

• Planning to receive adjuvant tamoxifen or anastrozole for 5 years

  • Eligible patients may receive adjuvant endocrine therapy on ICR-IBIS-II

• Hormone receptor status:

  • Estrogen receptor positive OR
  • Progesterone receptor positive
  • More than 10% tumor staining for receptor OR a cutpoint of ≥ 2

PATIENT CHARACTERISTICS:

Sex

• Female

Menopausal status

• Premenopausal, perimenopausal, or postmenopausal

Performance status

• Not specified

Life expectancy

• Not specified

Hematopoietic

• Not specified

Hepatic

• Not specified

Renal

• Not specified

Cardiovascular

• No prior deep vein thrombosis

Pulmonary

• No prior pulmonary embolus

Other

• No unexplained postmenopausal bleeding
• No contraindication to full-dose radiotherapy to the breast
• No other cancer within the past 5 years except nonmelanoma skin cancer or carcinoma in situ of the cervix

PRIOR CONCURRENT THERAPY:

Biologic therapy

• Not specified

Chemotherapy

• Not specified

Endocrine therapy

• See Disease Characteristics
• No prior tamoxifen or raloxifene use for more than 3 months in duration

Radiotherapy

• Not specified

Surgery

• See Disease Characteristics
• No prior mastectomy

Other

• No concurrent anticoagulants