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.