Roberts is taking her time off earlier than her planned medical leave for a bone marrow transplant. She had said previously that her medical leave would likely start at the end of August or early September.
The 51-year-old announced in June that she has myelodysplastic syndrome. MDS is a blood and bone marrow disease linked to the cancer treatment that once saved her life.
About 18,000 cases are diagnosed each year, and only a few hundred are caused by chemotherapy or radiation. Sometimes, cancer treatment can affect the DNA of blood-producing stem cells. Later, the fear is that it can turn into leukemia.
ABC News contributed to this report.
