Some doctors question new cancer treatment

The NanoKnife, which is also available in five hospitals outside the U.S., has so far been used to treat about 300 cancer patients world-wide. Doctors who have used the device say it has saved lives, including among prostate-cancer patients. While complications from the treatment have been reported in a few patients, some doctors say they are mainly concerned about what isn't known about the device because of a lack of evidence.