After its discovery, everyone presumed that something so energetic as radiation just had to be beneficial. In 1903, Pierre Curie, after observing burns on his arm left by the chunk of radium that he tied to it for 10 hours, concluded that he had discovered a cure for cancer.

I simply do not see his line of reasoning there – http://www.csmonitor.com/Innovation/Horizons/2011/1107/Marie-Curie-Why-her-papers-are-still-radioactive