The tumor was discovered last week during a colonoscopy.
Lab results and the timetable for Mancini’s recovery will not be known until next week.
“The outpouring of love and support I have received has made an extremely tough week so much better,” Mancini said in a statement. “I have the best family, friends, fans, and teammates imaginable. I am also eternally thankful for the Orioles front office, our athletic trainers, and the entire medical staff for everything they have done to help me during this time. Finally, I would like to thank everyone for their prayers and kind words, which have furthered my excitement to get back to playing the game I love.”
On Saturday, the Orioles announced Mancini had left the team to undergo what it called a “non-baseball medical procedure.”
“We are doing everything in our power to ensure Trey recovers fully, and we can’t wait to see him back on the field as soon as possible,” said Mike Elias, the team’s executive vice president and general manager.
The 27-year-old Mancini, who hit .291 with 35 home runs and 97 RBIs in 2019, played only five games this spring after earlier dealing with flu-like symptoms.
Mancini last played on March 2, but left the game after two at-bats.