Ron Edmonds, Associated Press
Tony Snow

Former White House press secretary Tony Snow, diagnosed with cancer three years ago, canceled a speaking appearance at Ohio's Ashland University because of an unspecified illness, the university announced Wednesday.

The university said Snow's doctors have told him he cannot travel and that Snow will be replaced by the president's brother, former Florida Gov. Jeb Bush, at today's fundraising dinner for the Ashbrook Scholar program.

Snow joined CNN as a conservative commentator in April. He became White House press secretary in April 2006 and served until last August.

In 2005, Snow had his colon removed and was diagnosed with cancer. In March 2007, he underwent surgery to remove a growth in his abdominal area. Doctors determined it was a recurrence of his cancer.

Ashland had no details on Snow's illness and CNN's public relations department had no immediate comment Wednesday