Radiation therapy seems to be the most effective although it is basically a shotgun approach for treatment. But consider this, we are constantly bombarded by different sources of radiation of one kind or another. Solar radiation, Americium 241 (AM-241) or Radium 226 (RA-226) found in smoke detectors, microwaves, etc are all part of our lives. It's just a matter of how long you are exposed to it. Lasers are very effective on pinpoint targets like tumor masses but not very practical for treating wide-range areas.