• Local tumor control (invasive and in situ local recurrence) [ Designated as safety issue: No ]
  

• Mastectomy rate [ Designated as safety issue: No ]
  
• Pattern of relapse in the breast [ Designated as safety issue: No ]
  
• Contralateral primary [ Designated as safety issue: No ]
  
• Breast cancer metastases [ Designated as safety issue: No ]
  
• Mortality [ Designated as safety issue: No ]
  
• Quality of life [ Designated as safety issue: No ]
  
• Molecular markers that predict ipsilateral tumor recurrence [ Designated as safety issue: No ]
  

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