In his first television interview since the operation, Robson told BBC Sport: "As soon as the specialist says it's a tumour that concerns you greatly.
"That's why the support from people all around the world has been fantastic. I feel fine and will carry on as normal."
Robson, who won 90 caps for England, has been Thailand manager since September 2009 and underwent surgery on his throat in Bangkok on 3 March.
Speaking to BBC sports news correspondent Dan Roan, Robson explained: "I just thought I had a sore throat but when I went to see the specialist he said he thought I had a tumour.
I'm going to try and continue [working with Thailand and Manchester United], it just depends the side effects of the treament
Bryan Robson
"He took it out and they've given me a course of treatment which I start in a couple of weeks, a five-week course. They are very confident I should recover 100%.
"As soon as I knew it was treatable you start relaxing and getting on with things. Thankfully I've caught it very early.
"You've just got to be positive, because the treatments nowadays are fantastic."
Robson has no intention to step down from the Thailand job, or as an ambassador for Manchester United, who he captained to three FA Cups, the 1991 European Cup Winners' Cup and two Premier League titles.
"I'm going to try and continue - I should be able to," he said. "It just depends the side effects of the treament. I will try and lead as normal a life as I can."
Robson also revealed he had received support from Geoff Horsfield and John Hartson - who played under him at West Brom and were later diagnosed with testicular cancer - and Brian Kidd, who was assistant manager when Robson played for Manchester United, and has suffered from prostate cancer.
"John [Hartson], Geoff Horsfield, have had similar problems and phoned me," Robson added. "I've had Brian Kidd on the phone to me today. You get on with things and its great when you've got fantastic support from everybody."
Source: BBC Sport
Source: BBC Sport