"Good Morning America" anchor Robin Roberts said she is starting chemotherapy for treatment of a disease that will require her to get a bone marrow transplant sometime this fall.
ABC's Roberts, who was treated for breast cancer five years ago, said she's been diagnosed with myelodysplastic syndrome, a blood and bone marrow disease once known as preleukemia.
The chemotherapy is a preparatory treatment for the bone marrow transplant. Roberts said her sister is a good match and has agreed to donate bone marrow.
"My doctors tell me I'm going to beat this, and I know it's true," Roberts said on the show Monday.
Roberts, 51, said she contracted the disease through her treatment for breast cancer. Between 80 percent and 90 percent of MDS patients develop it when they're over age 60, according to the American Cancer Society.
The Associated Press