U.S. FDA Resources

Enrollment:	5187
Study Start Date:	August 1998
Study Completion Date:	December 2010
Primary Completion Date:	January 2010 (Final data collection date for primary outcome measure)

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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

NCIC Clinical Trials Group

North Central Cancer Treatment Group

International Breast Cancer Study Group

Eastern Cooperative Oncology Group

Southwest Oncology Group

Cancer and Leukemia Group B

European Organization for Research and Treatment of Cancer - EORTC

Clinical trial summary from the National Cancer Institute's PDQ® database 

stage I breast cancer stage II breast cancer stage IIIA breast cancer

Breast Neoplasms Neoplasms by Site Neoplasms Breast Diseases Skin Diseases Tamoxifen Letrozole Antineoplastic Agents, Hormonal Antineoplastic Agents Therapeutic Uses Pharmacologic Actions

Selective Estrogen Receptor Modulators Estrogen Receptor Modulators Hormone Antagonists Hormones, Hormone Substitutes, and Hormone Antagonists Physiological Effects of Drugs Bone Density Conservation Agents Estrogen Antagonists Aromatase Inhibitors Enzyme Inhibitors Molecular Mechanisms of Pharmacological Action