Here's an article I just read:
In an interview published Monday, UFC President Dana White told TMZ about Fighters.com’s second-ranked heavyweight and UFC champion Brock Lesnar’s (4-1) medical condition, saying “There’s a possibility Lesnar will never fight again.”
White repeated his previous statements about Lesnar collapsing in Canada while recovering from mononucleosis and added, “[Lesnar] is very, very sick with an intestinal disorder that will require major surgery.”
White told TMZ he is trying to get Lesnar transferred to the Mayo Clinic.
Lesnar was scheduled to defend his UFC title from sixth-ranked Shane Carwin (9-0). The former All-American collegiate wrestler and WWE professional wrestling entertainer is one of the greatest athletes to enter MMA’s heavyweight division during the sport’s 16-year history and has the potential to evolve into one of the greatest fighters in MMA.
Sounds pretty awful, I don't really like the guy, but I hope he makes it out ok.