Conventional treatments for Cancer are not always successful, there is no question about that. The assertion that you can probably prevent 80% of most Cancer with the supplementation of Vitamin D and Selenium is fatally flawed as an argument. There is absolutely no tangible evidence in favor of this assumption, and by evidence I mean scientific research in favor of a direct correlation between Vitamin D and Selenium being 80% effective in the treatment of most Cancer. Save that, such statements are specious. Sad that we have not found a way to prevent Cancer, or to treat it effectively in all cases, and I understand the frustration with this, but to assert that supplementation of anything will probably cure 80% of Cancer cases without real proof is utterly absurd.