(Reuters) - Indianapolis Colts head coach Chuck Pagano is being treated for leukemia and is unlikely to resume full-time coaching duties this season, the National Football League team said on Monday.
The first-year coach, who turns 52 on Tuesday, was diagnosed with acute promyelocytic leukemia after feeling some fatigue in recent weeks and noticing bruising on his body that he initially thought came from contact during on-the-field coaching or while playing with his grandchildren.
Pagano, who was named head coach of the Colts in January, will be hospitalized for about six to eight weeks as he receives treatment and will be replaced by offensive coordinator Bruce Arians on an interim basis.
"I am optimistic. I feel with every fiber in my body and I know Chuck feels the same way, that he can beat this thing," Colts owner Jim Irsay told reporters.
"It's unlikely that he will be all-in as a head coach this season, that's probably not in the cards. ... Certainly to be in the press box, to contribute, to do things, I'm going to let the doctor be more specific about that with his expertise on how this process goes but there are peaks and valleys."
Pagano, who went 1-2 in his first three games as head coach of the rebuilding Colts, was diagnosed with the illness last week when the team had a bye week.
The former Baltimore Ravens defensive coordinator replaced Jim Caldwell, who was fired after a 2-14 season that sparked a massive rebuilding phase for the Colts, including a decision to cut 11-time Pro Bowl quarterback Peyton Manning.
Arians will make his debut as the Indianapolis head coach when the Colts host the Green Bay Packers on October 7.
(Reporting By Simon Evans in Miami; Editing by Frank Pingue and Gene Cherry)