The 54-year-old former midfielder had an operation to remove a tumour earlier this month and showed he was on the road to recovery by attending a football conference where he pondered his old club's pursuit of three trophies this season.
"The operation to remove the tumour was successful and now I've got to go on a course for five weeks of (radiotherapy) treatment," Robson told reporters at the Soccerex European business forum in Manchester.
"I'm feeling fine in myself. All the specialists have been really positive that I should have a 100 percent recovery. To be fair, that's all I wanted to hear, I'll just try to get on with the treatment and be as positive as I can be."
The former England captain has been watching United's season with interest as the Premier League leaders edge closer to a record 19th league title with an FA Cup semi-final and Champions League quarter-final also to look forward to.
But he said it might be too much to expect to win them all, like United did in 1999.
"I think it's a big ask to go and win a treble again," said Robson, who won two league titles and three FA Cups with United and is still an ambassador for the club.
"If you asked anybody at Man United at the moment if they could win two out of the three, I think they'd take that at this moment in time. But the aim will be to try to win the three."
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