Another preventative measure may be to ensure you have enough selenium in your diet. Apparently some Australian soils are selenium deficient.
"Selenium helps to prevent tissue damage caused by free radicals. Selenium is found in cereals, meat and fish. Cereals provide about 50% of dietary selenium. The selenium content of plant foods varies with the selenium content of the soil.
Cancer Council supports the National Health and Medical Research Council recommended dietary intake of 70μg/day for men and 60μg/day for women with an upper intake limit of 400μg/day (six times the recommended dietary intake). Selenium is safe if taken in moderation. However selenium supplements are toxic if taken in high doses.
Some studies suggest that selenium may be inversely associated with prostate cancer and colorectal cancer, but most of this evidence comes from trials designed to answer questions about other types of cancer. The evidence of a protective role of selenium in other types of cancers is weak and inconsistent. The true effects of selenium require confirmation in an independent trial(s) before new public health recommendations regarding selenium (either from dietary sources or as supplements) can be made.
Cancer Council does not support the use of health claims on food labels that suggest selenium protects against the development of cancer."
