Our own bacteria seem to be offering future keys to more effective cancer treatments.
Bacteria can affect cells in several ways, even change the DMA of cells and affect how much they reproduce, their immunity and metabolism.
Apparently understanding has increased so that now it is possible to engineer bacteria to trigger the immune system to fight some types of cancer. Whilst our tools are getting better, the more we learn the more we need to discover.
For more on this see: Popular Science Magazine and Science Magazine