This is nuts! This story was mentioned in the ASM news digest for this week–injecting spores of a species of “flesh-eating” Clostridium found in soil directly into tumors allows for the bacteria to effectively eat the tumor to get rid of it. They’ve already tried this in a person!
Primary article in Science: http://stm.sciencemag.org/content/6/249/249ra111
Popular article in Discover Magazine: http://blogs.discovermagazine.com/d-brief/2014/08/13/toxic-bacteria-devours-tumors-with-precision/#.U-5j-0hM77I