Letrozole After Tamoxifen in Treating Women With Breast Cancer

You may be eligible if

• DISEASE CHARACTERISTICS:
• Histologically or cytologically confirmed primary invasive breast carcinoma resected at time of original diagnosis
• * No ductal carcinoma in situ
• Axillary lymph node negative, positive, or unknown
• No evidence of metastases
• No localized or distant breast cancer recurrence
• Not registered on protocol NCCTG-893052, any other IBCSG protocol, or protocol SWOG-S9623
• Hormone receptor status:
• * Estrogen or progesterone receptor positive as defined by tumor receptor content at least 10 fmol/mg protein or receptor positive by ERICA or PgRICA
• * Unknown status allowed if effort to determine status has been made by immunocytochemistry
• No contralateral breast cancer
• PATIENT CHARACTERISTICS:
• Age:
• Postmenopausal
• Sex:
• Female
• Menopausal status:
• Postmenopausal defined by one of the following:
• * Age 50 or over at start of adjuvant tamoxifen
• * Under age 50 and considered postmenopausal by treating physician at start of adjuvant tamoxifen
• * Under age 50 at start of adjuvant tamoxifen and had bilateral oophorectomy (surgical or radiation)
• * Under age 50 and premenopausal at start of adjuvant tamoxifen, but became amenorrheic during tamoxifen and remained amenorrheic for at least 1 year
• * Considered postmenopausal by physician with LH/FSH levels under the treatment center's postmenopausal limits
• Performance status:
• ECOG 0-2
• Life expectancy:
• At least 5 years
• Hematopoietic:
• WBC ≥ 3,000/mm\^3 OR
• Granulocyte count ≥ 1,500/mm\^3
• Platelet count ≥ 100,000/mm\^3
• Hepatic:
• AST and/or ALT \< 2 times upper limit of normal (ULN) (unless imaging examinations have ruled out metastatic disease)
• Alkaline phosphatase \< 2 times ULN (unless imaging examinations have ruled out metastatic disease)
• Renal:
• Not specified
• Other:
• No concurrent medical or psychiatric condition that would preclude study participation
• No other malignancy within the past 5 years except adequately treated superficial squamous cell or basal cell skin cancer or carcinoma in situ of the cervix
• Able to swallow study drug
• Adequate oral intake
• PRIOR CONCURRENT THERAPY:
• Biologic therapy:
• Not specified
• Chemotherapy:
• Prior adjuvant chemotherapy allowed
• No concurrent chemotherapy
• Endocrine therapy:
• Completed at least 4.5 but no more than 6 years of adjuvant tamoxifen after resection
• Completed at least 4.5-6 years of adjuvant aromatase inhibitor as initial therapy or after tamoxifen
• No more than 3 months since prior adjuvant tamoxifen
• No concurrent hormone replacement therapy (e.g., megestrol)
• No concurrent selective estrogen-receptor modulators (e.g., raloxifene or idoxifene)
• Concurrent intermittent vaginal estrogens (e.g., Estring) allowed if other local measures for intractable vaginal atrophy are insufficient
• No other concurrent aromatase inhibitors
• No more than 2 years since prior aromatase inhibitor therapy (re-randomization)
• Radiotherapy:
• Prior radiotherapy allowed
• Surgery:
• See Disease Characteristics
• Other:
• At least 1 month since prior investigational drugs
• Prior treatment on a clinical trial for breast cancer allowed if permission has been obtained from the sponsors of the original study for their patient to participate on MA.17/JMA.17/BIG-97-01
• No prior placebo on core protocol
• No concurrent anticancer therapy
• Concurrent thyroid medication, calcium, vitamin D, and bisphosphonates allowed