• Overall survival (i.e., all-cause mortality) [ Designated as safety issue: No ]
  

• Specific-cause mortality [ Designated as safety issue: No ]
  
• Incidence of second primary tumors [ Designated as safety issue: No ]
  

OBJECTIVES:

• Assess the balance of risks and benefits in prolonging the duration of adjuvant tamoxifen by at least 5 years in patients with curatively treated breast cancer who have already had about 5 years of adjuvant tamoxifen.

OUTLINE: This is a randomized study. After about 5 years of adjuvant tamoxifen, recurrence-free patients are randomized to stop tamoxifen treatment immediately or to continue tamoxifen treatment for at least 5 more years.

Patients are followed annually.

PROJECTED ACCRUAL: Approximately 20,000 patients will be accrued for this study.

DISEASE CHARACTERISTICS:

• Curatively treated carcinoma of the breast

• Currently taking adjuvant tamoxifen

  • Must be substantial uncertainty as to whether or not to continue tamoxifen (i.e., no clear indication or definite contraindication to further treatment with tamoxifen)

PATIENT CHARACTERISTICS:

Age:

• Any age

Performance status:

• Not specified

Life expectancy:

• Not specified

Hematopoietic:

• Not specified

Hepatic:

• Not specified

Renal:

• Not specified

Other:

• Not pregnant or nursing
• No contraindications to receiving tamoxifen
• No other serious medical problems

PRIOR CONCURRENT THERAPY:

Biologic therapy:

• Prior biologic therapy allowed

Chemotherapy:

• Prior chemotherapy allowed

Endocrine therapy:

• See Disease Characteristics

Radiotherapy:

• Prior radiotherapy allowed

Surgery:

• Prior surgery allowed