Despite years of research and promising treatments, cancer remains one of the most deadly and persistent diseases for humans. Dr. Siddhartha Mukherjee discusses the history of cancer treatment, innovations in treating the disease, and the kinds of knowledge and research that needs to be shared to effectively fight cancer, at this year's Aspen Ideas Festival. He is one of the country's top cancer researchers and wrote the Pulitzer Prize-winning book, "The Emperor of All Maladies: A Biography of Cancer".