Immunotherapy: The new weapon in the fight against cancer

Yahoo Global News Anchor Katie Couric sat down with Dr. Siddhartha Mukherjee and filmmaker Ken Burns to discuss the new documentary “Cancer: The Emperor of All Maladies.” The six-hour, three-part film series, airing on PBS on March 30 and 31 and April 1, unravels the mystery of cancer through the patients who battle the disease and the researchers and scientists who have dedicated their lives to treating it.