Bugs as Cancer Drugs: Challenges and Opportunities.

The first nonsurgical cancer therapy was bacterial therapy introduced in 1891 to treat solid tumors. Because in many cases it was harmful and ineffective, and with the emergence of radiotherapy and chemotherapy, bacterial therapy was discontinued. Motivated by the need to improve targeting of solid tumors and in light of recent progress made in developing microbial therapies, the National Cancer Institute has for the first time issued funding opportunities to stimulate research on bacterium-based cancer therapies for conditions under which current cancer therapies are inadequate.