The Netherlands coach announced he was suffering from the illness on a Dutch television show earlier this month.
The news raised questions over whether Van Gaal would be well enough to lead the Oranje at this year's World Cup, set to take place in Qatar in November and December.
But now the ex-Barcelona and Manchester United boss has revealed he has successfully received a course of action against the cancer.
"I've been through everything," the 70-year-old told Dutch news agency ANP. "I had 25 radiation treatments. Then I had to wait five or six months to see if it had done its job. It did."
Van Gaal will step down after he has led his country at Qatar 2022, with the Oranje boss looking to better his third-place finish in charge at Brazil 2014.
It will bring the curtain down on his third spell at the helm of the national team, with another former boss in Ronald Koeman set to replace him.
Netherlands next face Belgium, Wales and Poland in their UEFA Nations League kick-off in June.