Sally O'Neill decided to have a double mastectomy rather than "do a wait-and-see." Richard Knox/NPR hide caption

itoggle caption Richard Knox/NPR

Some images of lung cancer are clear cut. But in many others, a nodule on the screen turns out not to be cancer at all. iStockphoto.com hide caption

itoggle caption iStockphoto.com

Dr. Joel Policzer checks on his patient, Lillian Landry, in the hospice wing of an Florida hospital in 2009. A new study found that many terminally ill cancer patients don't fully understand their prognosis. J. Pat Carter/AP hide caption

itoggle caption J. Pat Carter/AP

Back in 1998, Colleen Maxwell, then a 23-year-old student, smoked outside a San Diego bar, just weeks after California became the the first state in the nation to to ban smoking in most bars and gambling casinos. Joan C Fahrenthold/AP hide caption

itoggle caption Joan C Fahrenthold/AP

Dr. Steven Birnbaum positions a patient inside a CT scanner at Southern New Hampshire Medical Center in Nashua, N.H., in June 2010. Jim Cole/AP hide caption

itoggle caption Jim Cole/AP