Dayton told reporters that he learned of the diagnosis last week and that he might have surgery. He added that he plans to finish out his term and said, "I’m not in any pain.”
Dayton made the announcement in St. Paul after he gave his annual budget proposal. The announcement comes one day after he collapsed while giving his State of the State speech.
Dayton, who turns 70 on Thursday, said Tuesday he wasn't intending to disclose the diagnosis until deciding on a treatment plan, but last night's episode sped it up. His cancer treatment plan is not clear at this point.
Dayton said he had no reason right now to believe his fainting was connected to his prostate cancer diagnosis but added that he hoped to learn more after his doctor's appointment later Tuesday afternoon.
Dayton said he didn't sense problems last night until right before his collapse; he said he started to not feel well less than a minute before he fainted.
The governor said to laughter that the "speech was way too long ... that was the problem." He added, "next year it will be shorter."
The governor's chief of staff said in a statement last night that Dayton "quickly recovered" after fainting.
"Governor Dayton briefly fainted after speaking for about 40 minutes," Chief of Staff Jaime Tincher said. "He quickly recovered, walked out of the Capitol, and returned home."
Tincher added, "EMTs joined the governor there, and performed a routine check. He is now spending time with his son and grandson."