Proton beam therapy can precisely target tumors to avoid harming surrounding tissue, advocates say. Blythe Bernhard/St. Louis Post-Dispatch/MCT/Landov hide caption toggle caption Blythe Bernhard/St. Louis Post-Dispatch/MCT/Landov Shots - Health News Insurers Cautious As Proton Beam Cancer Therapy Gains Popularity Kaiser Health News September 23, 2014 Supporters of the controversial, high-priced treatment say routine coverage would help propel research that would support its use. Skeptics say that approach is backward.