"The tumour has been reduced now, that's good news," Doug Ford told reporters on Tuesday morning, in remarks that were broadcast live on CP24.
"Rob's going to be finished his fifth round of chemo in a few days and then from there, they're looking at some of the radiation."
He said that the Ford family members are optimistic about the news, but recognize that the former mayor has a long way to go.
"I'm all smiles today, but it's a long, long haul. It's not over yet,” he said, adding that "it's an emotional roller-coaster, not only for the person, but for their family and their friends."
When asked if he expected his brother to make a renewed bid for the mayor's office in four years' time, Doug Ford said that will depend on his health.
"That's a long ways off, but he loves politics, loves serving the people. I'm confident if he's healthy, he'll run," he said.
Doctors found a tumour in Ford's abdomen in September, a discovery that led him to withdraw from the mayoral race. Instead, Ford ran for a seat on council and was elected in Ward 2.
The 45-year-old was diagnosed with liposarcoma, a rare form of cancer, after doctors found the tumour.
Ford spoke to the Toronto Sun on Monday and told the newspaper that the tumour had shrunk from a size of 13 centimetres to approximately six centimetres.