Bacteria used to deliver radiation treatment to pancreatic tumors

Science : Pancreatic cancer is exceptionally lethalâmdash;only 4% of patients survive past 5 yearsâmdash;partly because of its aggressive metastasizing . Now a novel way to halt its spread has been proposed. Listeria monocytogenes is a bacterium that has previously been shown to directly attack tumor cells when it is modified to carry the tumor cells’ DNA. Claudia Gravekamp of the Albert Einstein College of Medicine in New York and her colleagues combined the modified Listeria with a radioactive compound and used it to treat mice with human pancreatic cancer tumors. The radioactive bacteria treatment reduced the number of metastatic cancer cells by up to 90%, while nonirradiated bacteria eliminated 50% of the metastasized cells. In addition, the radioactive bacteria shrank the primary tumor by 64% versus just 20% for the nonradioactive treatment. And there was very little damage to healthy tissue. Although a 90% elimination of metastasized cells is impressive, the remaining 10% are more than enough to be lethal. The researchers believe that use of a radiation source with a longer half-life could be 100% effective. Certain issues need to be addressed, however, before the treatment can be used on humans, including the risk of inducing sickness by using Listeria, which is itself a dangerous bacteria even in an attenuated form, and the potential buildup of radiation in the kidneys after the bacteria die.