A million people in the grave who used coffee enemas?  Where in the world do you get that figure, Bret?  I should point out that no one I know of recommends only doing coffee enemas for cancer.

Coffee stimulates the glutathione-S-transferasean enzyme system in the liver, which results in a very large increase in gultathione production.  The reason that rectal administration is best is that items administered rectally, such as therapeutic enemas, go directly to the liver via the hepatic portal vein system.  Coffee also stimulates and dilates the bile duct.  If the bile ducts are not open and flowing then the liver may have to endure too high a load of toxins from any successful anti-cancer protocol. 

I suppose you could just drink the coffee, but it would take liters of coffee to come close to the same benefits.