The Denver Post and Rocky Mountain News Tuesday both reported Karl will have surgery Thursday at the Huntsman Cancer Institute at the University of Utah in Salt Lake City.
The cancer is reported to be in the early stages. Karl has apparently known since April that he has prostate cancer.
Karl was named head coach of the Nuggets Jan. 27. He directed the team to the NBA playoffs, but they were beaten in the first round by the eventual champion San Antonio Spurs.
During his coaching career, Karl has a 740-507 record, including 32-8 with the Nuggets last season.