Always consult your doctor before taking any action that could affect your health.
"Selenium is a mineral that is being considered a crucial antioxidant which lowers your chance of getting Prostate cancer significanty. Countries like Canada whose soils have low levels of selenium also have higher rates of cancer including prostate cancer. A study done in the USA more than 14 years ago strongly supports the selenium-prostate cancer link. In a random group of men with skin cancer, half were given selenium and half were given a placebo. Although scientists found hat the mineral didn't decrease skin cancer recurrence, they discovered a 70% reduction in prostate cancer in men taking selenium! Since then, other researchers are finding similar results.
Caution: doses higher that 200 mcg of selenium a day may be toxic and cause extra health problems".
Source: "Eating Right for Life - Prostate Cancer Nutrition & you" ISBN O-9698972-8-6
http://www.cnn.com/HEALTH/men/9906/17/selenium.prostate/index.html