Robin Roberts Shares Emotional Update About Partner's Breast Cancer Battle (Exclusive)

Robin Roberts chats with ET and gives an emotional update on her longtime partner Amber Laign's breast cancer battle while promoting her book, 'Brighter by the Day' out now. The book's release coincides with a major milestone for the ABC News anchor: she's celebrating 20 years as co-host of 'Good Morning America!' In honor of the anniversary, ET takes Roberts on a trip down memory lane, watching back her first-ever interview.