Conditions: Colorectal Cancer Adenomatous Colorectal Polyps Precancerous Condition
Keywords: colon cancer rectal cancer colorectal cancer adenomatous polyp
Allocation: RANDOMIZED | Intervention model: PARALLEL
Enrollment: 1621
Healthy volunteers: yes

Brief summary:
RATIONALE: Chemoprevention therapy is the use of certain drugs to try to prevent the development or recurrence of cancer. Selenium may be effective in preventing the recurrence of adenomatous colorectal polyps.

PURPOSE: This randomized phase III trial is studying selenium to see how well it works in preventing the recurrence of polyps in patients with adenomatous colorectal polyps.

Detailed description:
OBJECTIVES:

Primary

* Compare the effects of selenium vs placebo on the recurrence of adenomatous colorectal polyps, in terms of histologic type, degree of dysplasia, number, size, and location, in patients with adenomatous colorectal polyps.
* Compare the type, incidence, and outcome of side effects in patients treated with these regimens.
* Determine patient adherence to long-term treatment with these regimens.

Secondary

* Determine the effects of regimen modification by baseline blood selenium level, low-dose aspirin, selenoprotein genetic marker polymorphisms (e.g., GPx-1, GPx-2, and SEP15)
* Determine the effects of low-dose aspirin (81 mg/day) modification by ornithine decarboxylase promoter genotype, and toxicity by slow-metabolizer genotypes of the cytochrome p450 2C9 and UT1A6 loci in these patients.

OUTLINE: This is a randomized, double-blind, placebo-controlled, multicenter study. Patients are stratified according to use of low-dose (≤ 81 mg/day) aspirin (yes vs no). Patients are randomized to 1 of 2 treatment arms.

* Arm I: Patients receive oral selenium once daily.
* Arm II: Patients receive oral placebo once daily. In both arms, treatment continues for up to 5 years\* in the absence of disease progression or unacceptable toxicity.

Patients undergo follow-up colonoscopy approximately 5 years\* after baseline colonoscopy.

NOTE: Some patients will continue participation for up to 7 and a half years

PROJECTED ACCRUAL: A total of 1,600 patients with an adenoma will be randomized to this study, followed by a second group of randomization of 200 patients with at least one advanced adenoma (at baseline) for a substudy. Total planned randomizations = 1,800 participants.

Arms:
arm 1: Participants receive oral selenium 200 mcg once daily. arm 2: Participants receive oral placebo once daily.

Interventions: intervention 1: Selenium
Intervention descriptions: intervention 1: Participants will be randomized either to selenium or placebo, taking the randomized intervention for 3 to 5 years, depending on when their recommended follow up colonoscopy is scheduled.

Protocol document: