Vitamin D Supplement in Preventing Colon Cancer in African Americans With Colon Polyps

RATIONALE: Chemoprevention is the use of certain drugs to keep cancer from forming. The use of vitamin D may keep colorectal cancer from forming in patients with colon polyps. PURPOSE: This randomized phase I trial is studying a vitamin D supplement to see how well it works compared with a placebo in preventing colorectal cancer in African Americans with colon polyps.

OBJECTIVES: Primary To determine the accrual rate of African Americans with adenomatous polyps to a 6-month randomized intervention trial comprising supplementation with either cholecalciferol (vitamin D3) or placebo. To determine the compliance rates in patients treated with these regimens. Secondary To compare changes in pre- and post-treatment vitamin D levels in patients treated with these regimens. To correlate vitamin D levels with vitamin D modifiers, such as levels of skin pigmentation, dietary vitamin D intake, and sun exposure in this patient population. OUTLINE: Patients are randomized to 1 of 2 arms. Arm I: Patients receive oral cholecalciferol (vitamin D3) supplementation daily for up to 6 months in the absence of disease progression or unacceptable toxicity. Arm II: Patients receive oral placebo supplementation daily for up to 6 months in the absence of disease progression or unacceptable toxicity. Patients complete questionnaires about demographics, dietary vitamin D intake, personal history (e.g., ancestry, alcohol and tobacco intake, occupation, height, and weight), medical history (e.g., personal and family history of colorectal cancer and polyps), and ultraviolet radiation exposure. Blood samples are collected at baseline and at 6 months for correlative laboratory studies. Blood samples are analyzed for vitamin D levels by enzyme immunoassay. Patients also undergo assessment of skin pigmentation in sunprotected and sunexposed areas of skin by reflectance spectrometry at baseline.

Patients receive oral cholecalciferol (vitamin D3) supplementation daily for up to 6 months in the absence of disease progression or unacceptable toxicity.

Patients receive oral placebo supplementation daily for up to 6 months in the absence of disease progression or unacceptable toxicity.

Correlation of vitamin D levels with vitamin D modifiers (e.g., levels of skin pigmentation, dietary vitamin D intake, and sun exposure)

DISEASE CHARACTERISTICS: Histologically confirmed adenomatous polyp At least 1 adenoma Self-identified as an African American AND undergoing screening or diagnostic colonoscopy at the University of Chicago No history of colon or rectal cancer or hereditary or familial colon cancer (e.g., hereditary non-polyposis colon cancer or familial adenomatous polyposis) PATIENT CHARACTERISTICS: Total bilirubin normal AST and ALT ≤ 2.5 times upper limit of normal Creatinine normal Albumin ≥ 3.0 mg/dL Baseline serum calcium level normal Not pregnant No history of thyroid disease No history of renal stones PRIOR CONCURRENT THERAPY: See Disease Characteristics No other concurrent vitamin D intake