Only on the "CBS This Morning" podcast, Amy Blumenfeld talks with "CBS This Morning" co-host Norah O'Donnell about her debut novel, "The Cast." The book is told through the various perspectives of a group of friends as they reunite to celebrate the protagonist's 25th year of remission from childhood cancer. Blumenfeld discusses her own battle with childhood cancer and how the characters and events in the book are loosely based on her life.