Traditional cancer therapies are limited for two key reasons: little of the drug actually reaches the tumor and the drug is toxic to both cancerous and healthy tissues.

Bacteria, however, have the potential to precisely target cells. "In a way, bacteria are the ultimate in smart drugs. "It's hard to pack a lot of intelligence into a small molecule or protein; but bacteria can have sensors and actuators and can drill into a cell, like a submarine."

Most people know E. coli as bacteria that can cause deadly food poisoning. In the future, though, it may save lives as a treatment for cancer. cancer cells were used in the E. coli experiments agent Breast for removing multiple myeloma cells from stem cells used in autologous transplantation. Multiple myeloma, a cancer of the immune system cells that are responsible for producing antibodies, is very resistant to standard doses of chemotherapy. One of the risks of the procedure is the tumor cells might not always be caught and could be returned to the patient with the stem cells. Using the shiga-like toxin-1 (SLT-1) from E. coli, the researchers were able to destroy cancer cells from human stem cell cultures. The cells were exposed to the toxin in a test tube, and neither the toxin nor the intact bacteria were ever given to the patients, thereby avoiding the symptoms of E. coli food poisoning. The cancer cells used in their experiments were multiple myeloma, B-cell lymphoma, and breast cancer.

But Cancer bacteria are infectious organisms that are known or suspected to cause cancer. While cancer-associated bacteria have long been considered to be opportunistic (i.e., infecting healthy tissuesaftercancer has already established itself), recent evidence is showing that some bacteria may be directly involved in causing some cancers. The strongest evidence to date involves the bacteriumH.pyloriand its role in gastric cancer.