Good Morning America host Robin Roberts has Breast Cancer

Robin Roberts announced Tuesday that she has breast cancer and will be undergoing surgery Friday.

Roberts, 46, made the surprising announcement with co-host Diane Sawyer by her side, saying she wanted everyone to hear it from her. Roberts said she discovered the lump the day they did the tribute show for Joel Siegel who died of complications from colon cancer last June 29. She contacted her doctor, who told her to have a mammogram and an ultrasound. She said the cancer was not detected in the mammogram, but the ultrasound found it.