DISEASE CHARACTERISTICS:

* Postmenopausal women at increased risk for developing invasive breast cancer, who meet one of the following criteria:

* At least 12 months since spontaneous menstrual bleeding
* Prior documented hysterectomy and bilateral salpingo-oophorectomy
* At least 55 years of age with prior hysterectomy with or without oophorectomy
* Age 35 to 54 with a prior hysterectomy without oophorectomy OR with a status of ovaries unknown with documented follicle-stimulating hormone level demonstrating elevation in postmenopausal range
* Histologically confirmed lobular carcinoma in situ treated by local excision only OR a minimum projected 5 year probability of invasive breast cancer of at least 1.66%, using Breast Cancer Risk Assessment Profile
* No clinical evidence of malignancy on physical exam within the past 180 days
* No evidence of suspicious or malignant disease on bilateral mammogram within the past year
* No bilateral or unilateral prophylactic mastectomy
* No prior invasive breast cancer or intraductal carcinoma in situ
* Hormone receptor status:

* Not specified

PATIENT CHARACTERISTICS:

Age:

* 35 and over

Sex:

* Female

Menopausal status:

* See Disease Characteristics

Performance status:

* No restricted normal activity for a significant portion of each day

Life expectancy:

* At least 10 years

Hematopoietic:

* Granulocyte count at least 1,500/mm\^3
* Complete blood count and differential normal
* Platelet count normal

Hepatic:

* SGOT or SGPT normal
* Bilirubin normal
* Alkaline phosphatase normal

Renal:

* Creatinine normal

Cardiovascular:

* No cerebral vascular accident, transient ischemic attack, atrial fibrillation, or uncontrolled hypertension
* No deep vein thrombosis

Pulmonary:

* No pulmonary embolus

Other:

* No other prior malignancy within the past 5 years except basal cell or squamous cell skin cancer or carcinoma in situ of the cervix
* No concurrent nonmalignant disease that would preclude administration of tamoxifen or raloxifene
* No clinical depression, psychiatric condition, or addictive disorder
* No uncontrolled diabetes

PRIOR CONCURRENT THERAPY:

Biologic therapy:

* Not specified

Chemotherapy:

* Not specified

Endocrine therapy:

* At least 3 months since prior estrogen or progesterone replacement therapy, oral contraceptives, androgens, luteinizing hormone-releasing hormone analogs, prolactin inhibitors, or antiandrogens
* At least 3 months since prior tamoxifen, raloxifene, or other selective estrogen-receptor modulators of less than 3 months duration
* Concurrent Estring allowed

Radiotherapy:

* No prior breast radiotherapy

Surgery:

* See Disease Characteristics

Other:

* No prior systemic adjuvant therapy for breast cancer
* No other participation in a cancer prevention or osteoporosis prevention study involving pharmacologic intervention(s)

* NSABP-P-1 patients who received placebo are eligible
* No concurrent warfarin or cholestyramine
* Concurrent calcitonin or nonhormonal medication (e.g., cholecalciferol, fluoride, or bisphosphonates) allowed