Selenium and Prostate Cancer: Clinical Trial on Availability to Prostate Tissue and Effects on Gene Expression
Rationale: Prostate cancer is a frequently observed malignancy in men, especially in elderly
men. Besides diagnosis and treatment, also prevention of prostate cancer is an important
point of interest to reduce the incidence and mortality of prostate cancer. Selenium is
considered to be a promising chemopreventive agent for prostate cancer. Exact mechanisms of
chemoprevention by selenium are not fully understood. However, it is expected that selenium
(among other effects) directly affects gene expression in the prostate.
Objective: The aim of this study is to get insight into bioavailability of selenium in
prostate tissue and changes of gene expression profiles that might be responsible for
selenium-induced chemoprevention. To meet this objective, the relationship between dietary
selenium intake and changes in gene expression profiles, tissue selenium levels and blood
flow in prostate tissue will be examined.
Study design: The present study is designed as a double-blind, randomized and
placebo-controlled intervention trial. Blood samples, toenails, questionnaires, MR images
and surgical specimens will be collected to examine effects of selenium supplementation.
Study population: The study population will consist of 60 men, diagnosed with prostate
cancer and scheduled for radical prostatectomy. Written informed consent will be obtained
from each participant.
Intervention: Participants will receive 300 ug selenium / day or a placebo during 5 weeks
prior to radical prostatectomy. Selenium will be supplemented in the form of selenized yeast
tablets (SelenoPrecise, Pharma Nord).
Main study parameters: Levels of selenium in prostate tissue and changes in prostate gene
expression profiles of participants supplemented with selenium or placebo, compared before
and after the short intervention period, will be considered as the main parameters of the
present study. Besides gene expression profiles in prostate tissue, also gene expression
profiles of peripheral mononuclear cells (PBMC), levels of selenium in blood and toenails
and blood flow and permeability of blood vessels of prostate tissue will be analyzed.
Allocation: Randomized, Endpoint Classification: Bio-availability Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Caregiver, Investigator, Outcomes Assessor), Primary Purpose: Prevention
selenium levels in prostate tissue
after 5 weeks of intervention with selenium or placebo
J.A. Witjes, Md PhD Prof
University Medical Center St Radboud
Netherlands: Medical Ethics Review Committee (METC)