The "Good Morning America" anchor announced on the ABC show Monday morning that she has been diagnosed with myelodysplastic syndrome, a blood and bone marrow disease once known as preleukemia.
She says she will undergo chemo and a bone marrow transplant this year as "pretreatment" for the disease, which she says she has known about for several weeks. She says her sister is a great match for her. While she says she'll miss a day here and there, she'll remain on the air.
Roberts battled breast cancer five years ago.
(Copyright 2012 The Associated Press. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.)