08/30/2012 at 08:25 AM EDT
After announcing this week
that Friday would be her last day on Good Morning America
before she began an extended medical leave
, Robin Roberts moved up the date of her departure to Thursday, reports ABC News
"I'm having to move up my schedule," the anchor, 51, said at the top of the show on Thursday. Roberts explained that she will first fly home to Mississippi to be with her ailing, 88-year-old mother, Lucimarian, and her family in the Hurricane Isaac zone.
Roberts will then be treated for myelodysplastic syndrome
(commonly called "MDS") and is starting preparations to undergo a bone-marrow transplant.
Roberts's sister, Sally, is the bone-marrow donor. Looking radiant but concerned for her sister, Sally said on Thursday's show, "Recovery time is so quick."
This week, leading to Roberts's farewell, Good Morning America
shared the stories of others battling MDS.
"It's rare to have MDS and mine was because of complications from the breast cancer treatment," said Roberts, who fought breast cancer
five years ago.
"I am very blessed," she added. "Forty percent of Americans can't even take a sick day, and here I know that I'm going to have a job when I come back."
On Thursday's GMA
, Roberts promised her colleagues that she would be "watching [them] in her jammies," and that thinking of their times on the show together would put her in her happy place.
"I know the journey ahead will not be easy," said Roberts, with a nod to the support she's received, "but I'm going to focus on all these gifts."
And while she noted that there is "no timetable" for her recovery and return to the show, she said, "Just know that I'm going to come back here as soon as I can."