Here's the reason why people including Napster billionaire Sean Parker are investing millions in this new type of cancer treatment

Spencer Platt/Getty Images Another big name has joined the research effort for a new kind of cancer treatment called immunotherapy, which uses the immune system to fight cancer cells.   Sean Parker, the internet billionaire who co-founded Napster and is a former Facebook president, gave $250 million on Wednesday to launch the Parker Institute that will help with the research and development of cancer immunotherapy treatments.  Unlike chemotherapy, which involves administering powerful drugs...