Folate-Depleted Diet Compared With Folate-Supplemented Diet in Preventing Colorectal Cancer in Patients at High Risk for Colorectal Cancer

DISEASE CHARACTERISTICS:

* Healthy persons at increased risk for colorectal neoplasia due to 1 of the following reasons:

  * Personal history of colorectal adenomatous polyps
  * Family history of colorectal adenoma or adenocarcinoma
* No history of multiple family members with colorectal neoplasia that is suggestive of dominant hereditary neoplasia

PATIENT CHARACTERISTICS:

Age

* 40 to 72

Performance status

* Ambulatory

Life expectancy

* At least 6 months

Hematopoietic

* No excessive bleeding or coagulation disorder

Hepatic

* ALT or AST ≤ 2 times upper limit of normal
* No unexplained elevated alkaline phosphatase

Renal

* Creatinine ≤ 2.0 mg/dL

Cardiovascular

* Homocysteine concentration ≤ 17um/L
* No sustained blood pressure \> 150/95 mm Hg for 3 consecutive readings

Other

* Vitamin B\_12 ≥ 250 pg/mL
* Folate level ≤ 20 mg/dL
* HIV negative
* Not pregnant or nursing
* Negative pregnancy test
* Fertile patients must use effective contraception during and for 4 weeks after study participation
* No intestinal malabsorption or inflammatory bowel disease
* No prior malignancy except nonmelanoma skin cancer
* No calcium metabolism abnormalities or predisposing conditions, such as hyperparathyroidism
* No untreated hyperthyroidism
* No untreated insulin-requiring diabetes mellitus
* No daily alcohol intake \> 2 ½ shot glasses of whiskey or three 8 ounce glasses of beer or wine
* No other serious illness that might limit life expectancy to \< 6 months

PRIOR CONCURRENT THERAPY:

Biologic therapy

* None

Chemotherapy

* None

Endocrine therapy

* No concurrent hormone replacement therapy, including oral, transplanted, or injected contraceptives
* Concurrent thyroid hormone replacement is allowed as long as the patient is euthyroid for 3 months

Radiotherapy

* None

Surgery

* No prior gastrointestinal surgery, including gastrectomy or small or large bowel resections

  * Prior appendectomy or surgery of the esophagus allowed

Other

* More than 3 months since regular ingestion of ≥ 650 mg per day of aspirin (≥ 2 tablets of 325 mg regular strength OR \> 1 tablet of 500 mg extra strength aspirin)
* More than 3 months since regular daily ingestion of nonsteroidal anti-inflammatory drugs
* At least 1 month since vitamin, mineral, or herbal supplementation
* No other concurrent vitamin, mineral, or herbal supplementation
* No concurrent anticoagulants
* No concurrent sterol-binding resins (i.e., cholestyramine)
* No other concurrent investigational drugs or medications that might alter rectal mucosal proliferation, folate metabolism, or renal/hepatic impairment
* No concurrent weight control medications
* No concurrent supplemental folate preparations containing \> 400 mcg of folic acid per day
* No concurrent lipid-lowering medications

  * The following concurrent statin drugs are allowed provided patient has been taking a stable dose for ≥ 1 month:

    * Atorvastatin 10 or 20 mg/day
    * Fluvastatin 20 or 40 mg/day
    * Lovastatin 10 or 20 mg/day
    * Pravastatin 10 or 20 mg/day
    * Simvastatin 5 or 10 mg/day