Anastrozole or Tamoxifen in Treating Postmenopausal Women With Ductal Carcinoma in Situ Who Are Undergoing Lumpectomy and Radiation Therapy

DISEASE CHARACTERISTICS:

• Histologically confirmed ductal carcinoma in situ (DCIS) of the breast
• Mixed DCIS and lobular carcinoma in situ (LCIS) allowed
• Must have undergone lumpectomy
• Margins must be histologically free of disease
• Re-excision to obtain tumor-free margins allowed
• No more than 84 days since prior lumpectomy or re-excision
• More than 1 area of DCIS allowed provided all disease is removed with tumor-free margins
• Masses or clusters of calcification that are clinically or mammographically suspicious must be biopsied
• No prior invasive breast cancer or DCIS
• Patients with a history of LCIS are eligible
• No prior or concurrent invasive (including microinvasive) breast cancer
• DCIS "suspicious" for microinvasion allowed
• No bilateral malignancy
• No mass or mammographic abnormality suspicious for malignancy in the opposite breast unless not malignant as proven by biopsy
• No Paget's disease of the nipple
• No positive ipsilateral axillary or intramammary nodes
• No palpable nodes in the ipsilateral or contralateral axilla or palpable supraclavicular or infraclavicular nodes unless not involved with tumor as proven by biopsy
• Hormone receptor status:
• Estrogen- or progesterone-receptor positive as determined by immunohistochemistry
• Borderline results are considered positive

PATIENT CHARACTERISTICS:

Age

• See Menopausal status

Sex:

• Female

Menopausal status:

• Postmenopausal as defined by at least 1 of the following:
• Prior documented bilateral oophorectomy
• At least 12 months without spontaneous bleeding
• Age 55 or over with prior hysterectomy without oophorectomy
• Age 54 or under with prior hysterectomy without oophorectomy with a documented follicle-stimulating hormone level in the postmenopausal range

Performance status

• Zubrod 0-2

Life expectancy

• At least 10 years (excluding diagnosis of breast cancer)

Hematopoietic

• WBC normal

Hepatic

• AST normal
• Bilirubin normal
• Alkaline phosphatase normal
• No hepatic disease that would preclude administration of study drugs

Renal

• Creatinine normal
• No renal disease that would preclude administration of study drugs

Cardiovascular

• No prior documented cerebral vascular accident or transient ischemic attack
• No prior deep vein thrombosis
• No cardiovascular disease that would preclude administration of study drugs
• No uncontrolled hypertension (i.e., systolic blood pressure at least 180 mm Hg or diastolic blood pressure at least 110 mm Hg based on the average of 2 or more readings at each of 2 or more visits after initial screening)
• No uncontrolled atrial fibrillation

Pulmonary

• No pulmonary embolus

Other

• Not pregnant or nursing
• Patients with a history of non-breast malignancies are eligible provided they have been disease-free for ≥ 5 years and are deemed by their physician to be at low risk for recurrence
• No other malignancy within the past 5 years except treated basal cell or squamous cell skin cancer, carcinoma in situ of the cervix, carcinoma in situ of the colon, or melanoma in situ
• No psychiatric or addictive disorders that would preclude informed consent
• No uncontrolled diabetes, defined as hemoglobin A1C greater than 9% (fasting glucose 200 mg/dL)
• No nonmalignant systemic disease that would preclude administration of study drugs

PRIOR CONCURRENT THERAPY:

Endocrine therapy

• No prior or concurrent aromatase inhibitors (e.g., exemestane or letrozole) or tamoxifen
• No concurrent raloxifene or other selective estrogen receptor modulators
• No concurrent sex hormone therapy (e.g., estrogen or progesterone replacement therapy, oral contraceptives, androgens, luteinizing hormone releasing hormone analogs, prolactin inhibitors, or antiandrogens)
• Low-dose estrogen vaginal creams or Estring allowed

Radiotherapy

• Radiotherapy for this cancer initiated before study is allowed

Surgery

• See Disease Characteristics
• No prior or concurrent mastectomy for DCIS
• Prior sentinel node bio